Ezmlm lists and the From header

13May09

If you have used the fine ezmlm mailing list manager (which is a perfect complement for the qmail MTA) you may have found that when hitting the “Reply” button in your mail client, the recipient will be the author of the message instead of the list address. There is a quick workaround by passing the list address to the -3 to ezmlm-make, but that will screw up the “From” MIME header in messages, and it will look like all messages were send by the mailing list!

Fortunately, there is a solution thanks to the infinite tuneability of ezmlm. As you should already know, for each list a directory with some files is created for each mailing list, and most of the behaviour of the mailing list can be tuned by editing those files. There are two files which affect MIME headers which will be of interest:

• headerremove defines a list of headers which will be stripped off messages when they arrive.
• heeaderadd defines a list of headers (and their values) which will be added by ezmlm when processing messages.

What we want to do is that the “Reply” button of mail clients makes them use the list address as recipient. For this we can add a “Reply-To” header, and a “X-Mailing-List” one (the latter is not standard, but honored by a number of clients):

  echo 'Reply-To: yourlist@yourdomain.com' >> headeradd
  echo 'X-Mailing-List: <yourlist@yourdomain.com>' >> headeradd

The we must ensure that the original “From” header is preserved, by not listing it in headerremove:

  sed -i -e '/^[Ff]rom$/d' headerremove

Now you will see the correct “From” value in messages, and replying to them will send the message to the list by default. Also, if you want to filter list messages, you can now use the “X-Mailing-List” header, which is the default action of some clients when classifying messages per mailing list.

Isn’t ezmlm nice?

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