Knowledgebase

Log sender rates in the exim mainlog

This option allows you to log sender rates in the Exim mail log.

Sender Verification Callouts

This option allows Exim to connect to the mail exchanger for a given address and verify that it exists before accepting messages from it.

Smarthost support

This option allows you to use a Smarthost for outgoing messages.

To configure this option, enter a valid route_list in the Smarthost support text box. For example, to configure a smarthost which uses one IP Address, enter an asterisk (*) followed by an IP Address. This will resemble the following: * 192.188.0.20

To configure a Smarthost which uses multiple domains, enter an asterisk, followed by the IP addresses. You should separate each IP Adresswith a colon. This will resemble the following:

* 192.188.0.20 : 192.188.0.21: 192.188.0.22

Important Do not forget to precede hostnames or IP addresses with an asterisk.

For more information about route_lists, read the Exim route_list documentation.

EXPERIMENTAL: Rewrite From: header to match actual sender

This option rewrites the From header in emails to show the original identity of the actual sender for messages sent from your server. Email recipients can see the original From header as X-From-Rewrite along with the rewritten From header. This option is useful to determine the actual mail sender. The following example shows the From and X-From-Rewrite response:

From: [email protected]
X-From-Rewrite: rewritten was: [[email protected]], actual sender is not the same system user

Note: This option does not affect mail received from a remote host. The From header is only rewritten for mail that is sent from the local machine because it is not possible to determine or validate the actual mail sender from remote machines.

Through WHM, system administrators have 3 options:

In order to conduct an attack or send unsolicited email, a malicious user can alter the From field in an email to confuse the recipient. For example, a user may be authenticated as [email protected] and send a message with the From header set to [email protected]. When this option is enabled, the From header will be rewritten to show the actual sender, which in this case is [email protected].

To avoid a potential problem, a system administrator can enable this option to ensure that the From header for mail sent from their server always matches one of the following:

Send generic recipient failure messages

This option allows you to send the following message to senders who attempt to send an undeliverable message: "The recipient cannot be verified. Please check all recipients of this message to verify they are valid."

Allow mail delivery if malware scanner fails

This option allows you to disable the malware scanner if it fails. If you select On (the default setting), then in the event of a malware scanner failure, all mail will be delivered as normal.

Note: If you select Off and the malware scanner fails, users will not receive new messages until the scanner is repaired.

Reject mail for users over quota

This option allows you to reject SMTP-time mail for users who have exceeded their quota, rather than directing the mail into their queue.

Sender Verification

This option allows you to verify the origin of mail senders.

Set SMTP Sender: headers

This option allows you to set the Sender: header as "-f flag passed to sendmail" when a mail sender changes.

Note: The default setting is Off.

Note: If you set this option to Off, Microsoft® Outlook will not add an "On behalf of" header. This may limit your ability to track abuse of the mail system.

Allow mail delivery if spam scanner fails

This option allows you to disable the spam scanner if it fails. If you select On, all mail will be delivered as normal in the event of a spam scanner failure.

Note: The default setting is On.

Note: If you select Off and the spam scanner fails, users will not receive new messages until the scanner is repaired.

Trust X-PHP-Script headers to determine the sender of email messages sent from processes running as nobody

This option allows messages that are sent with X-PHP-Script headers to be trusted when sent from the user 'nobody'. This option also enables the mail server to determine the true sender. This will provide a faster delivery process than a query to the Apache server to determine the sender.

Note: It is possible for an advanced user to forget this header. If your users may misuse this function, disable this option and send a query to the Apache server to determine the sender of 'nobody' messages.

Query Apache server status to determine the sender of email messages sent from processes running as nobody

This option allows the mail delivery process to query the Apache server to determine the true sender of a message when the nobody user sends a message. This option requires an additional connection to the webserver for each message that is sent by the user account nobody (when suPHP and mod_ruid2 are both disabled).

This option is more secure, but it is faster to trust the X-PHP-Script headers.

This option defaults to On.