[Patch] ''Content-Transfer-Encoding'' header not allowed in the main mime container

[Thomas Moschny]

(At least the) ticket notification mails sent by the plugin contain in the main header the fields:

Content-Type: multipart/related; charset="utf-8"; boundary="..."
Content-Transfer-Encoding: base64

According to RFC 1521 (5. The Content-Transfer-Encoding Header Field) that is invalid (and may confuse certain email clients, hence the ticket):

"Certain Content-Transfer-Encoding values may only be used on certain Content-Types. In particular, it is expressly forbidden to use any encodings other than "7bit", "8bit", or "binary" with any Content- Type that recursively includes other Content-Type fields, notably the "multipart" and "message" Content-Types. All encodings that are desired for bodies of type multipart or message must be done at the innermost level, by encoding the actual body that needs to be encoded."

To fix the problem, the "Content-Transfer-Encoding:" field could simply be removed from the main header of the messages. This is valid and the standard value "7bit" will be assumed.

[Robert Corsaro]

(In [7137]) Remove Content-Transfer-Encoding from main mime container fixes #6171

[Thomas Moschny]

In 1.0_a1 (r8410) the problem is there again.

[Thomas Moschny]

Here's the trivial patch:

announcerplugin/distributors/email_distributor.py

@@ -313 +313 @@
         else:
             alternate_output = None
         rootMessage = MIMEMultipart("related")
-        rootMessage.set_charset(self._charset)
         proj_name = self.env.project_name
         trac_version = get_pkginfo(trac.core).get('version', trac.__version__)
         announcer_version = get_pkginfo(announcerplugin).get('version', 

[Robert Corsaro]

(In [8862]) Remove invalid content-transfer-encoding

Fixes #6171 Thanks thomas.moschny@…!

[Thomas Moschny]

Would you mind applying that tiny patch also to the 0.11 branch?