What is Mailman's "full personalization" option?

By default, newly created lists have the Mailman "personalization" option (found in the "Non-digest options" section of the Mailman settings) set to "Full Personalization".

This causes the "headers" of each list message to appear like this when the subscriber receives them:

To: "Subscriber Name" <subscriber address>
Cc: "List Description" <list address>

There are two reasons this is the default. The first is that if you think about it, it's technically correct: the mailing list software has indeed sent this particular message to this subscriber, and it has indeed CC:ed the message to the other members of the list. The headers accurately match the list message the subscriber receives.

But there's a more important reason for it, too. Some spam filters (including the hotmail.com spam filter) check whether the recipient's name or address are contained in an incoming message's "To" header. If the header contains the recipient's name or address, the filter is less likely to mark it as "spam". In our tests, "full personalization" noticeably decreases the likelihood that a list message will end up in a user's "Junk" or "Spam" folder.

So in general, using full personalization is a good idea, and you almost certainly don't want to change it if you're concerned about your messages appearing as "spam" to your subscribers.

What if I want to change it anyway?

Some people prefer the "To:" header to contain only what the original sender included — something like:

To: <list address>

... without including the recipient's address in the headers, and without adding a separate CC: header.

You can easily change your list to work this way:

  • Login to the Mailman settings page.
  • Click Non-digest options.
  • Locate the "personalization" section.
  • Change "Full Personalization" to Yes. (Do not change it to "No"; doing so is unnecessary and would prevent each user from getting a customized "unsubscribe" footer.)

Changing the personalization to "Yes" causes Mailman to use the "To:" header from the original message as the "To:" header of the message it sends to each subscriber. In most cases, that "To:" header will contain the list address (although that's not guaranteed if you let other people post to the list, because a sender might put the list address in a "CC:" or a "BCC:" header of the original message instead of the "To:" header).