MS - DKIM - Yahoo

[+JustCh4pman+]

I'm running into some issues with DKIM and what I believe to be the headers which are added to messages by Mailscanner. (I'm a paid customer of the MailScanner install service)

Recently after an update to MailScanner, we started seeing the Mailscanner headers display in *body* of outgoing messages.

Now Yahoo is blocking our messages due to message content - "554 Message not allowed - [299]"

Going into MS configuration, under Changes To Message Headers, I noticed the comments in "Place New Headers At Top Of Message" about Multiple Headers and Place New Headers at top of message. I followed the advice there, this did not resolve the issue. It actually broke delivery to Gmail, fyi. Changing to any combo other than the default setting breaks Gmail and never resolves the issue with Yahoo.

I think there may be a bug in how those headers are added to messages and it may be setting off Yahoo's content filtering. On Yahoo's help site, for error 554 they list "For example, it is against Yahoo Mail's policy to accept messages with malicious content or manipulated header information"

Thoughts?

[Sarah]

The only time we have seen headers end up in the message body with MailScanner is when the setting for "%org-name%" contains a space or punctuation. Make sure that setting ONLY contains letters and/or numbers, no spaces or special characters.

Regards,
Sarah

[+JustCh4pman+]

I've verified, no spaces or special characters. Like I said before, MS was working fine before the last update. That's when the headers started showing up in the body.

I have performed a force-update, which did not fix the issue.

[+JustCh4pman+]

I just disabled watermarking and messages are delivered to Yahoo. It's something in Watermarking.

[+JustCh4pman+]

Using the DKIM tester here: appmaildev DOT com

with Watermarking enabled, the DKIM will fail with an error: Wrong body hash. With Watermarking disabled, DKIM passes.

I'm totally guessing here... the watermarking headers are added *after* the DKIM body hash is generated, making it invalid. It could be total coincidence that Yahoo is maybe being more stringent about the DKIM hashes?

Whatever end result, it's definitely the Watermark headers causing the issue.

Thoughts?

[Sarah]

If you think it is a bug within MailScanner I would suggest posting it to the MailScanner newsgroup:
http://lists.mailscanner.info/mailman/l ... ailscanner