Tuesday, October 23, 2012

SMTP Custome Error Codes

SUMMARY
Error codes that can be displayed in the SMTP debug and activity log files.
DETAIL
The easiest way to determine why inbound messages are not being processed by the SMTP connector is to examine the SMTP Activity and Debug logs. The logs can be found in the MailEnable Admin MMC -> Servers -> Localhost -> Connectors ->SMTP Logs.
These log files record SMTP transactions and their associated response codes.
These response codes are explained further with possible resolutions below:


220 Service ready
Error Description: This response is sent from the SMTP server when a remote SMTP client or host has successfully connected to the SMTP service.
221 Service closing transmission channel
Error Description: This response is sent from the server when the remote server/client has notified that it is closing the connection. You would commonly notice this command after a QUIT command was received.
250 Requested mail action okay, completed
Error Description: This response indicates that a SMTP command was received by the server and successfully processed.
354 Start mail input; end with .
Error Description: This response is sent by the SMTP server and instructs a remote SMTP server or client that the DATA command was accepted and that it can commence sending the actual message. A message consists of;
[first the message headers],[CRLF].[CRLF] then
[the actual message body],[CRLF].[CRLF]
421 Service not available, closing transmission channel
Error Description: This response is sent by the SMTP server to a remote SMTP server or SMTP client to indicate that the MailEnable SMTP Server is currently unavailable.

Error Resolution: When this error is returned in the logs or to a client then it usually means that the data store in particular the configuration directory data cannot be accessed.
When using a default install of MailEnable you can check and repair the permissions on the MailEnable TAB delimited configuration files by comparing and/or executing the commands in step 6 of the following article:

Article ME020073
If you have changed your default installation to use the MailEnable database provider and are using an SQL database server while getting this error then ensure that the database is online. If the database is online then ensure MailEnable services are able to connect and retrieve data from the database tables you may also find errors for this within the server Event Logs.
451 Requested action aborted: error in processing
Error Description: This response is sent by the SMTP server to a remote SMTP Server or SMTP client to indicate that the MailEnable SMTP Server is currently unable to complete the transaction or command. There can often be more information contained within the SMTP debug logs for this error.

Error Resolution:When this error is returned in the logs or to a client then it usually means that the data store in particular the configuration directory data cannot be accessed. The first thing to check is that your hard drive is not full or faulty or in some cases ensure that any quotas enabled on the drive are not being exceeded. Information on these types of problems can usually be found in the server Event Logs.
When using a default install of MailEnable you can check and repair the permissions on the MailEnable TAB delimited configuration files by comparing and/or executing the commands in step 6 of the following article:
Article ME020073
If you have changed your default installation to use the MailEnable database provider and are using an SQL database server while getting this error then ensure that the database is online. If the database is online then ensure MailEnable services are able to connect and retrieve data from the database tables.
451 Temporary server error. Please try again later.
Error Description: This response is sent by the SMTP server to a remote SMTP Server or SMTP client to indicate that the MailEnable SMTP Server is currently unable to complete the transaction or command. There can often be more information contained within the SMTP debug logs for this error.

Error Resolution: When this error is returned in the logs or to a client then it usually means that the data store in particular the configuration directory data cannot be accessed. The first thing to check is that your hard drive is not full or faulty or in some cases ensure that any quotas enabled on the drive are not being exceeded. Information on these types of problems can usually be found in the server Event Logs.
When using a default install of MailEnable you can check and repair the permissions on the MailEnable TAB delimited configuration files by comparing and/or executing the commands in step 6 of the following article:

Article ME020073
If you have changed your default installation to use the MailEnable database provider and are using an SQL database server while getting this error then ensure that the database is online. If the database is online then ensure MailEnable services are able to connect and retrieve data from the database tables.
451 Requested action aborted: This mail account has sent too many messages in a short amount of time. Please try later.
Error Description: Means that the SMTP configuration setting to limit the the quantity of messages sent per hour has been reached. The message sent in this instance has failed and will need to be retried by the client.
Error Resolution: This feature is disabled by default. You can review this and increase the configured amount of messages per hour or accept the error as correctly limiting a sender or domain.
In the MailEnable Professional or Enterprise manual the settings can be found at:
Post Office Restriction - Administration->Post Office configuration->Restrictions->Limit Maximum SMTP recipients
Mailbox Restriction - Administration->Post Office actions->Create Mailbox->Restrictions->Limit SMTP usage to a maximum of

451 This server employs greylisting as a means of reducing spam. Please resend e-mail shortly
Error Description: This is the temporary error returned to a connecting server when they try to send to an address for the first time while the MailEnable Greylisting spam protection feature is enabled.
Error Resolution: You can in this situation disable the Greylisting service or whitelist the connecting IP. By whitelisting the IP in the Greylisting feature options it means that when this server connects to the MailEnable SMTP service next it will bypass the Greylisting check.
In the ME Admin MMC the option is configurable at:
Note: MailEnable Professional version users can set this feature at a global level only so the first configuration option below applies. Enterprise users as with most features can also configure this at a post office and mailbox level.
ME Admin MMC->Servers->Localhost->SMTP "Properties"->Greylisting (TAB)
In the MailEnable Professional or Enterprise manual the setting can be found at:
Greylisting Global Configuration - Configuration of connectors, services and agents->SMTP Connector->SMTP - Greylisting
Post Office Restriction - Administration->Post Office configuration->Feature Selection->Force Greylisting for all users
Mailbox Restriction - Administration->Post Office actions->Create Mailbox->Spam->Enable Greylisting
451 The IP Address you are sending from was reported as a source of spam. Please contact your e-mail administrator.
Error Description: If a connecting IP has been found in a configured DNS blacklist then this error can be returned to the client and server.
Error Resolution: The best resolution in this case if you want to receive messages from the sending server is to alert the connecting server administrator that they are listed on a blacklist and need to get themselves removed. In some cases it can be easier to whitelist their IP in the SMTP whitelist option as this will bypass any Blacklist checks on the inbound. You can find out more on this rejection in the SMTP debug logs it should also list the blacklist name that the connecting IP was found in.
Note: We are assuming that the default setting in the blacklisting action feature is set to "Dont Accept Email". If this setting is configured to "Mark As Spam" then the message will be accepted and processed by internal filter actions.
In the MailEnable Professional or Enterprise manual the settings can be found at:
Global Restriction - Configuration of connectors, services and agents->SMTP Connector->SMTP Reverse DNS blacklisting
451 ESMTP MailEnable Service temporarily refused connection at [time] from IP [xxx.xxx.xxx.xxx] because the server is too busy
Error Description: When the SMTP service inbound connection limit is reached the service will reply with this temporary error. Usually in this situation the remote server will automatically retry the send to the service.
Error Resolution: This error is a warning and it should be reveived and considered correctly if increasing this inbound thread limit for the error. The default setting for this feature restriction is 32 connections or threads which for most servers will be enough. In high throughput servers you may find that this limit needs to be increased and as such you increase it as you feel, usually 256 is enough for most servers.
If this limit is being reached then you can check the SMTP activity logs and see how many connections you are getting before the error is returned in the logs. While checking make sure the inbound connections appear to be valid and not all coming from one IP or one domain/sender if they are repeating then you should use the other information in the logs to check if the messages are legitimate or the sender needs blocking.
The limit is in place to help prevent spammers or hackers from completing a DOS attack on the server and sending an unlimited and untimed connection based attack to your server.
In some cases if this error continues it can be a good idea to review your DNS Blacklisting service. If you have too many blacklists or one blacklist is timing out on connection then it can tie up your inbound connections for too long. The best way to check this is to disable all blacklists except one along with disabling the URL blacklisting to see if it helps.
Article ME020343
In the MailEnable Professional or Enterprise manual the setting can be found at:
Configuration of connectors, services and agents->SMTP Connector->Inbound->Maximum number of concurrent connections
452 Too many recipients
Error Description: Means that the SMTP configuration setting to limit the inbound recipients per transaction or message has been exceeded.
Error Resolution: This error is a warning and it should be reviewed and considered correctly if increasing this limit. The limit is in place to help prevent spammers or hackers from completing a DOS attack on the server and sending to a large amount of recipients in one connection. You may need to increase or disable this setting if you are sending mail outs as this error can be triggered when you are trying to send a mail out from a script or send mail program.
Article ME020268
In the MailEnable Professional or Enterprise manual the setting can be found at:
Configuration of connectors, services and agents->SMTP Connector->SMTP - Security->Restrict the number of recipients per email
452 You are not permitted to send to remote domains
Error Description: When this error is shown in the client and/or logs it means that the internal MailEnable configuration setting to limit a mailbox, post office or server has been enabled. By default this setting is not enabled but when changed it can prevent a singular mailbox, or all mailboxes in a domain or even on the server to only be able to send locally to their own domain.
Error Resolution: If this error is believed to be in error then it can be disabled in the ME Admin MMC. In each of the configuration options below you can change the option to allow the mailboxes to send to local and remote domains or restrict mailboxes to only send to local addresses.
Note: MailEnable Professional version users can set this feature at a global level only so the first configuration option below applies.
The first place to check for this setting is at the global level in the ME Admin MMC at:
ME Admin MMC->Servers->Localhost "Properties"->Policies (TAB)->Sender Policy
If the setting above is set to the option "Sending policy determined by postoffice" then you need to check the following place:
ME Admin MMC->Post Offices->[Post Office Name] Properties->Restrictions (TAB)->"The sender policy determines whether users can only send messages to a local domain"
If the above setting is set to "Sending policy determined by mailbox" then you need to check the following place.
ME Admin MMC->Messaging Manager->Post Offices->[Post Office Name]->Mailboxes->[Mailbox Name] "Properties"->Restrictions (TAB)->"User can only send to their local domain"
In the MailEnable Professional or Enterprise manual the settings can be found at:
Global Restriction - Administration->Server Configuration->Policies->Sender Policy
Post Office Restriction - Administration->Post Office configuration->Restrictions->Same Domain Restriction
Mailbox Restriction - Administration->Post Office actions->Create Mailbox->Restrictions->Local Sender Restriction
500 Message rejected because it contains links to an IP address that is blacklisted
Error Description: As a message is being received the SMTP service will resolve links in the message and check these against the configured blacklist. If the destination IP from the resolve is listed in a configured blacklist the message will be rejected with this error.
Note: We are assuming that the default setting in the blacklisting action feature is set to "Don't Accept Email". If this setting is configured to "Mark As Spam" then the message will be accepted and processed by internal filter actions.
Note: When URL blacklisting is executed we check the first section of the message only, about 20 lines. Checking large messages with many links can affect performance. In most situations, if not all, this is enough as spammers do not tend to send many links or large messages.
Error Resolution: The best resolution if you want to receive messages from the sending server is to alert the connecting server administrator that they are sending message links that are listed on a blacklist. In some cases it can be easier to whitelist their IP in the SMTP whitelist option as this will bypass any URL Blacklist checks on the inbound. You can find out more on this rejection in the SMTP debug logs it should also list the blacklist name that the connecting IP was found in.
In the MailEnable Professional or Enterprise manual the settings can be found at:
Global Restriction - Configuration of connectors, services and agents->SMTP Connector->SMTP Reverse DNS blacklisting
500 Syntax Error, command unrecognized
Error Description: This error means that a remote client or server has sent a command that is not recognized by the MailEnable SMTP service.
Error Resolution: The best way to find out more about this error is to check the SMTP activity log at the time of the connection as the command will be listed in the log transaction.
501 Syntax error in parameters or arguments
Error Description: This error means that the remote server is sending incorrect commands through to the server. Often this can occur when the message contains a line that is too long and as such cannot be read by the MailEnable SMTP service.
Error Resolution: Check the SMTP activity and debug logs in this situation as there should be more information on what is occurring. If the logs do not help then check how the message is being sent to see if you can find anything that is abnormal.
501 Invalid Address
Error Description: This error means that the address format used in the sending client is not correct. Usually this is checked in a standard retail client but when using scripts or web pages it may not be the case.
Error Resolution: Check the SMTP activity logs as they should show what format and what characters are being used for the addresses. Check in particular for incorrect characters, here is a list of correct email address characters;

Use any ASCII alphanumeric character plus (`!', `#', `$', `% `&', `*' `+', `-' `~', and whatever you can find in between ASCII 33 and 47).
In short, you should use lower case characters, numbers and the underscore to create your email address.
501 Your domain does not seem to be valid, Could not find MX record for your domain.
Error Description: This error means that the sending email address contains a domain that is not a registered domain name.
Error Resolution: This check is done when the following feature is enabled. The sender should check their email client settings and ensure that their configured email sender address contains a correct and valid domain name after the @ sign.
In the MailEnable Professional or Enterprise manual the setting can be found at:
MailEnable Manual - Configuration of connectors, services and agents->SMTP Connector->SMTP -Security->reject mail if sender address is from an invalid domain
502 Command not implemented
Error Description: This error means the remote client or server is trying to send a command that is not supported by the SMTP service.
Error Resolution: Use the SMTP activity logs to find out what command was sent to the MailEnable SMTP service. The commands that MailEnable lists and can use are listed in the SMTP service on the Advanced SMTP tab if the command is not listed then it is not supported or incorrect. On this tab the commands can also be enabled or disabled the feature can be found in the following location of the ME Admin MMC:
ME Admin MMC->Servers->Localhost->Connectors->SMTP "Properties"->Advanced SMTP (TAB)->Allowed SMTP commands
503 Bad sequence of Commands
Error Description: The error means that the remote client has sent a command to the server that is not in the correct and recognised order for the SMTP service.
Error Resolution: Use the SMTP activity logs to find out what the commands were and that they were issued in the correct order.
503 Bad sequence of commands. You must specify the recipients of a message before you can send it
Error Description: The error means that a client or server has tried to send a message to the MailEnable SMTP service without the presence of or a correct SMTP address in the TO, CC or BCC field.
Error Resolution: Check the client that is sending and determine why it is not correct you may also find out more in the MailEnable SMTP activity log.
503 Bad sequence of commands. Could not process DATA command when in this state
Error Description: The error means that a client or server has tried to send a message to the MailEnable SMTP service but has sent the DATA command out of sequence.
Error Resolution: Check the client that is sending and determine why it is not correct usually you will see that the client is sending a DATA command while the SMTP service is expecting another command like RCPT TO, EHLO
503 Bad sequence of commands. Could not process RCPT command when in this state
Error Description: The error means that a client or server has tried to send a message to the MailEnable SMTP service but has sent the RCPT TO command out of sequence.
Error Resolution: Check the client that is sending and determine why it is not correct. Usually you will see that the client is sending a RCPT TO command while the SMTP service is expecting another command.
503 This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server.
Error Description: This error means that the server or client has connected to the MailEnable SMTP service but has not entered a RCPT TO mail address that exists on the server but the domain for the incorrect address does reside on the server. The order of checks in this situation are;
1. Does the domain exist on the server (Yes)
2. Does the address exist in the address-map.tab file or table on the server (No)
3. Has the client authenticated. (Due to earlier No at 2 this check has not occurred.
As the connection has not authenticated meaning that one of the options above in 1 or 2 have not been met then the error is returned.
Error Resolution: The resolution here really resolves around when you think this error is being returned when it should not be. If the address is thought to exist on the server then you need to check the SMTP logs activity for the transaction and then the debug to see if there are any error descriptions that better explain what happened when the address was sent to. Then you should check your configuration to ensure that the address does exist. It can also be a good idea to check the address-map.tab file in the MailEnable\Config directory or relevant database table for a line that contains the mailbox name in question. If you are checking why the sender could not relay through the server then you should at this time check the client settings and ensure that the outbound settings in the client are configured as such so they can relay through the server to non local email addresses.
Article ME020198
503 Too many invalid commands were received. Terminating Session
Error Description: This error means that the threshold of the MailEnable SMTP security feature has been reached for too many invalid or unrecognized commands sent to the server.
Error Resolution: If this error is not working the way you expected then you can disable the feature or increase the configured limit so the connection is not dropped prematurely.
In the ME Admin MMC the option is configurable at:
ME Admin MMC->Servers->Localhost->SMTP "Properties"->Security (TAB)->Connection Dropping
In the MailEnable Professional or Enterprise manual the settings can be found at:
Configuration of connectors, services and agents->SMTP Connector->SMTP Security->Drop a connection when the failed number of commands or recipients reaches
504 Access to this user account has been denied by the mail administrator
Error Description: When this error is returned to a client it means that the mailbox has been configured by an administrator to not allow authentication.
Enterprise users may have a mailbox placed into this reject authentication status if the mailbox reaches the Server Password Policy lockout limit.
The Server Password Policy lockout limit in the ME Admin MMC is configurable at:
ME Admin MMC->Localhost "Properties"->Policies (TAB)->Password Policies
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Server configuration->Policies
Error Resolution: You can remove the mailbox authentication lock from the mailbox in the mailbox properties within the ME Admin MMC.
In the ME Admin MMC the option is configurable at:
ME Admin MMC->Messaging Manager->Post Offices->[Post Office Name]->Mailboxes->[Mailbox Name] "Properties"->General (TAB)->Prevent user from authenticating.
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Post office actions->Create mailbox->General->Prevent user from authenticating
504 User account has been disabled by the mail administrator
Error Description: When this error is returned to a client it means that the mailbox has been configured by an administrator to not allow authentication.
Enterprise users may have a mailbox placed into this reject authentication status if the mailbox reaches the Server Password Policy lockout limit.
The Server Password Policy lockout limit in the ME Admin MMC is configurable at:
ME Admin MMC->Localhost "Properties"->Policies (TAB)->Password Policies
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Server configuration->Policies
Error Resolution: You can remove the mailbox authentication lock from the mailbox in the mailbox properties within the ME Admin MMC.
In the ME Admin MMC the option is configurable at:
ME Admin MMC->Messaging Manager->Post Offices->[Post Office Name]->Mailboxes->[Mailbox Name] "Properties"->General (TAB)->Prevent user from authenticating.
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Post office actions->Create mailbox->General->Prevent user from authenticating
550 Requested action not taken: mailbox unavailable or not local
Error Description: This error means that the server or client has connected to the MailEnable SMTP service but has not entered a RCPT TO mail address or domain that exists on the server. The address is checked in the local configuration files in particular the address-map.tab file or database table.
Error Resolution: The resolution here really resolves around when you think this error is being returned when it should not be. If the address is thought to exist on the server then you need to check the SMTP activity logs for the transaction and then the debug to see if there are any error descriptions that better explain what happened when the address was sent to. Then you should check your configuration to ensure that the address does exist. It can also be a good idea to check the address-map.tab file in the MailEnable\Config directory or relevant database table for a line that contains the mailbox name in question.
550 Requested action not taken. The domain you are sending from is not permitted to access this server
Error Description: When this error is returned to a client it means that the domain has been blocked from sending to any address in the receiving post office.
In the ME Admin MMC this is configurable at:
ME Admin MMC->Post Offices->[Post Office Name]->Domains->[Domain Name] "Properties"->Blacklist (TAB)->Domains
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Post office actions->Create domain->Blacklist
550 This mail server requires authentication (0) when attempting to send via this SMTP (submission) port
Error Description: When this error is received it means that the MailEnable server SMTP service has been configured to force all inbound connections to authenticate. This setting is designed mainly for servers that want all mail to come from a remote spam checking service as it forces connections that send to and through the server to authenticate unless they are allowed relay by IP. All other connections even when simply sending to the server will fail with this error if this is not the case.
In the ME Admin MMC this is configurable at:
ME Admin MMC->Servers->Localhost->SMTP Properties->Inbound (TAB)->"Properties"->Port Settings [Button]->SMTP Port->"Requires connections to authenticate before sending email"
Or for alternate SMTP listening port:
ME Admin MMC->Servers->Localhost->SMTP Properties->Inbound (TAB)->"Properties"->Port Settings [Button]->Submission Port->"Requires connections to authenticate before sending email"
In the MailEnable Professional or Enterprise manual the settings can be found at:
Configuration of connectors, services and agents->SMTP Connector->Inbound->Requires connections to authenticate before sending email
Error Resolution: The resolution is determined by whether you want this feature to be enabled or not. If you are getting this error when you are not expecting then ensure that this feature is not enabled for either SMTP port. If you require this feature and understand what it does then ensure any servers that are required to send through the server and not authenticate are added to the inbound IP relay list.
551 User not local: authentication required for relaying
Error Description: This error means that the server or client has connected to the MailEnable SMTP service but has not entered a valid MAIL FROM mail address. The address is checked in the local configuration files in particular the auth.tab file or database table.
This error can also mean that the mailbox that has been entered into the MAIL FROM address line is local on the server but has been disabled on the server by a server administrator or in some cases a control panel.
Error Resolution: The resolution here really resolves around when you think this error is being returned when it should not be. If the address is thought to exist on the server then you need to check the SMTP logs activity for the transaction and then the debug to see if there are any error descriptions that better explain what happened when the from address was entered. Then you should check your configuration to ensure that the address does exist. It can also be a good idea to check the auth.tab file in the MailEnable\Config directory or relevant database table for a line that contains the mailbox name in question.
If the mailbox has been disabled then you can find the setting for this in the following location.
In the ME Admin MMC this is configurable at:
ME Admin MMC->Messaging Manager->Post Offices->[Post Office Name]->Mailboxes->[Mailbox Name] "Properties"->General (TAB)->Domains->Mailbox is disabled
In the MailEnable Professional or Enterprise manual the settings can be found at:
Administration->Post office actions->Create mailbox->General->Logon disabled
551 Sender address is not valid for your login. Check your email program settings
Error Description: This error is returned when a client is connecting to relay through the MailEnable server and has authenticated with a correct mailbox address but in the sender field of the mailbox the address does not match. If this was not prevented it means that a mailbox on the server can authenticate correctly as one address but be able to send with a different from address in effect the sender would be creating a forged email.
Error Resolution: If you want to allow these email addresses to be different then you will need to disable the security feature in the SMTP options.
In the ME Admin MMC this is configurable at:
ME Admin MMC->Servers->Localhost->Connectors->SMTP "Properties"->Security (TAB)->Authenticated senders must use valid sender address
In the MailEnable Professional or Enterprise manual the settings can be found at:
Configuration of connectors, services and agents->SMTP Connector->SMTP Security->Authenticated senders must use valid sender address
552 Message size exceeds fixed maximum message size
Error Description: This error is displayed when either the configured SMTP inbound or outbound limit has been exceeded.
Error Resolution: You can find out about which SMTP option either inbound or outbound was the one that prevented the message by checking the SMTP activity logs. If the message is inbound in the log you will see SMTP-IN at the start of the line if the message was restricted while leaving the server (outbound) then the log line will contain SMTP-OU.
The inbound SMTP limit is configurable at the following location:
ME Admin MMC->Servers->Localhost->Connectors->SMTP "Properties"->Inbound (TAB)->Advanced Settings |Button|->Advertised maximum message size + Enforce this message size
The outbound SMTP limit which places a limit on relayed messages is configured at the following location:
ME Admin MMC->Servers->Localhost->Connectors->SMTP "Properties"->Outbound (TAB)->Limit outbound message size

554 The IP address of the sender (xxx.xxx.xxx.xxx) was found in a DNS blacklist database and was therefore refused
Error Description: This error means that an inbound connection has been detected as being listed in one of your configured DNS blacklists within the SMTP options.
To find out more about this feature check the MailEnable manual:
In the MailEnable Professional or Enterprise manual the settings can be found at:
Configuration of connectors, services and agents->SMTP Connector->Reverse DNS blacklisting
Error Resolution: The resolution in this situation varies depending on the inbound connection itself and your verification of the validity of the sender. In short if the sender is blacklisted and you want to receive mail from this sender then you should suggest/request that they remove themselves from the blacklist (Click here for more) Article ME020166. In some situations this resolution can be too slow or troublesome and as such you can either stop checking this particular blacklist by removing it from the SMTP blacklist options configuration or you can add the connecting IP to the Whitelist of the SMTP service this will ensure that any future connections from this IP bypass the blacklist check.

554 The IP address of the sender (xxx.xxx.xxx.xxx) does not match the SPF record for the sender domain
Error Description: This error correlates to the SPF checking feature within the MailEnable SMTP service settings. The SPF feature checks for a valid SPF record to be configured in DNS and then acts on this according to your actions configured in the SPF feature within ME Admin MMC.
To find out more about this feature check the MailEnable manual:
In the MailEnable Professional or Enterprise manual the settings can be found at:
Configuration of connectors, services and agents->SMTP Connector->Sender Policy Framework (SPF)
Error Resolution: In a similar manner to the Blacklisting feature the resolution in this situation varies depending on the inbound connection itself and your verification of the validity of the sender. If the sender is rejected in this situation and you want to receive mail from this sender then you should suggest/request that they correct their SPF record and /or ensure that they have one configured (Click here for more) Article ME020345. In some situations this resolution can be too slow or troublesome and as such you can either turn off the checking of SPF altogether or you can add the connecting IP to the Whitelist of the SMTP service this will ensure that any future connections from this IP bypass the SPF check.

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