3.59. Why are some of my users getting the error "Your mail to ... is being held ... Message has a suspicious header"?

Question: Some of my users are trying to post to my mailing list, and I've checked and confirmed that their "moderate" bit is not set, but they are still getting an error message back that says:

 Your mail to 'Example-list' with the subject

     Why are my messages being held?

 Is being held until the list moderator can review it for approval.

 The reason it is being held:

     Message has a suspicious header

 Either the message will get posted to the list, or you will receive
 notification of the moderator's decision.  If you would like to cancel
 this posting, please visit the following URL:

Why is this?

Answer: This is a result of the "legacy spam filters" being applied to incoming messages. Mailman 2.1 added some new features for spam filtering, but also continues to provide access to the legacy spam filters as well. Older versions of Mailman have only the legacy spam filters. With the legacy spam filters, you can define certain regular expressions in the headers that you're looking for, and any message that comes in with these patterns will be held for moderation, and a message will be sent to the poster to inform them that their message is being held for "suspicious headers" (see above).

By default, the standard header regular expressions that will be searched for are:

 to: friend@public.com
 message-id: relay.comanche.denmark.eu
 from: list@listme.com
 from: .*@uplinkpro.com

However, as list administrator, you can go to the "Privacy..." section of the web admin page for your list, then go to the "Spam filters" subpage, and add more regular expressions to search for. For Mailman 2.1.x, these regular expressions would go in the "legacy anti-spam filters" box at the bottom of the page, while earlier versions of Mailman would simply have the one box for all anti-spam filters. If you wish to delete these legacy anti-spam filters for your list, you can do that by selecting all the entries with your mouse, "cutting" the text, and then clicking on the "Submit Your Changes" button at the bottom of the page.

The site administrator can control the default settings for what legacy anti-spam filters will be applied by changing the value of DEFAULT_BOUNCE_MATCHING_HEADERS in the Mailman/mm_cfg.py file. The format for this can be found in the Mailman/Defaults.py file, although actually changing the defaults should be done in Mailman/mm_cfg.py – otherwise, when Mailman is upgraded, the Mailman/Defaults.py file will also be upgraded, and all your site changes will be lost. During an upgrade, Mailman/mm_cfg.py will not be changed, which is why we recommend that all site-specific changes be made there.

Converted from the Mailman FAQ Wizard

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