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http://bugs.exim.org/show_bug.cgi?id=1096 Summary: Add mailfrom option to recipient callout Product: Exim Version: N/A Platform: Other OS/Version: All Status: NEW Severity: wishlist Priority: medium Component: ACLs AssignedTo: [email protected] ReportedBy: [email protected] CC: [email protected] Right now as I understand it recipient callouts are limited to two sender options, either an empty sender, or using the original sender. Keep in mind that my application is that I'm running a front end spam filtering service where I accept email for thousands of domains, clean it, and forward to the end user's servers. The servers I forward to are not under my control, and often are not under the control of the customer either. (The customer's ISP has control). Therefore I have to be able to adapt to a wide variety of conditions that I can not control. The reason I do recipient verification is because if the recipient doesn't exist on the customer's server I want to know that at SMTP time so that I can reject the email while they are still connected rather that produce a separate bounce email later. The disadvantage of an empty sender is that some people implement "back-scatter protection" to by hostile to sender address verification. But this configuration is also hostile to recipient verification as well. When using the original sender the disadvantage is that the caching is based on sender recipient pairs so that a separate callout must be done if multiple senders are sending to the same recipient. That increases the bandwidth usage and the higher number of connections sometimes triggers connection count greylisting delays on the recipient server side. So - my thinking is that if there were a mailfrom option on recipient callouts then I could use something like "[email protected] as the sender and avoid both of the above problems. Additionally this address would appear in the customer's logs and would let them know what the connection was about. (As opposed to "I got this connection but it never sent any email") Since mailfrom is already in sender verification it should be easy to allow in recipient verification. Can I suggest it be a hidden feature (undocumented) if there are concerns for 4.75 and then fully implement it in 4.76? -- Configure bugmail: http://bugs.exim.org/userprefs.cgi?tab=email -- ## List details at http://lists.exim.org/mailman/listinfo/exim-dev Exim details at http://www.exim.org/ ##
