I am a member of a list which uses mailman 2.1.2, and I am experiencing strangeness in Outlook as a result of the modifications mailman performs on list posts. Specifically, when it (re)folds the Subject: and/or Thread-Topic: headers, it replaces a space character in the original subject with a tab character.

According to RFC 2822 §2.2.3, unfolding one of these lines consists of only removing the CRLF. As a result, what had been a subject of the form "source_line1 source_line2" is now "source_line1\tsource_line2" in the mailman-altered mail, which is incorrect, and is displayed oddly by Outlook (due to some differences between tabs and space characters). (The other modification to the subject line, specifically, the addition of the "[mailinglist] " string, is fine.)

When wrapping header lines, mailman should only insert (or move around) CRLFs and retain the original WSP characters from the original, lest issues like these arise.

Is this a known issue, or should I post a new bug?

Thanks in advance, Nathan

Nathan Herring MacBU SDE/Development