#283 users.sourceforge.net needs to implement SRS to avoid issues with sender domains who have enabled SPF

[David Sommerseth]

I have for some time had issues receiving mail from certain senders which comes from domains who have enabled stricter SPF rules. The issue explained:

bob@example.com sends to jane@users.sourceforge.net

Mail is received by sf.net and forwarded to jane@another.domain.com. The mail which is forwarded have bob@example.com as the envelope sender.

Since example.com have a strict SPF rule, stating that mail from the example.com only comes from their own server, the forwarded mail gets rejected by the mail server hosting another.domain.com. Because the mail doesn't come from example.com's mailserver, but mx.sourceforge.net.

Other mail servers may also use SPF to flag mails as spam instead of rejecting them, and may as well just drop the mail and not bounce it.

The solution is to use SRS, which will rewrite the envelope sender, to a domain you control. In addition you can use SPF on that domain, to further restrict/avoid abuses (f.ex. that srs.sourceforge.net only sends mails via a:mx.sourceforge.net). Then mails will go straight through the SPF checks on the receiving side.

For more info:
https://en.wikipedia.org/wiki/Sender_Rewriting_Scheme
http://www.openspf.org/Why?s=mfrom;id=bob@example.com;ip=216.34.181.68;r=jane@another.domain.com

kind regards,

David Sommerseth