Patch — Return-Path headers should not be added to the message by TurboMail.

[fs]

TurboMail inserts a Return-Path header in every mail sent. The - now obsolete - RFC 822 stated:

4.3.1.  RETURN-PATH

   This field  is  added  by  the  final  transport  system  that
   delivers  the message to its recipient.  The field is intended
   to contain definitive information about the address and  route
   back to the message's originator. (...)

TurboMail is definitely NOT the final transport system, therefore this header should be omitted.

RFC 2822 does not say anything particular about when to insert the Return-Path header but states:

The trace fields are a group of header fields consisting of an
optional "Return-Path:" field, and one or more "Received:" fields.

I interpret this as there may be only ONE Return-Path header. Inserting two of them as TurboMail does when smtpfrom is not None, should be always wrong.

Furthermore, TurboMail inserts a header named 'Old-Return-Path' which does not appear in any of the RFCs.

With the attached patch no Return-path or Old-Return-Path headers are inserted anymore by TurboMail.

[fs]

new version which does not include the fix for #14 (can't replace the original diff as I don't have TRAC_ADMIN privileges)

[amcgregor]

Applied a slightly modified patch to work around test suite weirdness in r29. (Differences between my version and your version of basic_tests.py.)