You can use the Mailman pages to invite new recipients to join your list. This process also verifies the e-mail addresses to make sure that the address is correct.
To do this, click Membership Management, then Mass Subscription on the Mailman administration pages. You'll see a screen that allows you to "Invite/Verify" new e-mail addresses.
You should always use the "Invite/Verify" option on that page. Doing so is almost always required by our spam policy for your own protection: it completely protects you against false spam allegations.
When you invite new users, Mailman verifies the addresses for you by sending the following message:
Subject: Verify your example.com ListName subscription
Please follow the instructions below to join the example.com "ListName" mailing list. You will not be subscribed if you ignore this message.
To join the list, just reply to this message. Your reply will be sent to a special address that adds you to the list. The text of your reply does not matter and will not be seen by a human being.
If you prefer to use a Web browser to verify your subscription, please visit this Web page instead:
http://lists.example.com/something
If you don't want to subscribe to this list, please ignore this message. If you have any questions, please send a separate message to listname-owner@example.com.
The recipient then has 20 days to either reply or click the link to be added to the list. This step is what protects you against false spam accusations: when someone replies or clicks that link, it provides permanent evidence that the person at that address actually agreed to subscribe (and was not mistakenly added because someone mistyped their own e-mail address or something like that).
If we later receive spam complaints from verified addresses, we'll know the complaints are invalid and your list won't be affected. If people at verified addresses complain to other ISP or anti-spam blacklist operators, we can use the verification records to make sure the ISP or blacklist doesn't permanently block your mail.
You can change the subject and add additional text to the top of this message. In fact, we recommend doing so to include more information about your list. For example, you could include some text emphasizing that recipients won't be added to the list unless they reply to the verification message. You could also remind them that they gave you the addresses at, say, a school board meeting, and describe the purpose of the list.
Adding that kind of detail makes sure they won't mistake the verification message for "spam". But do keep it to the point: the idea is to get people to subscribe to the list, and that should be the focus of anything you add. If you have something else to tell them, do it separately after they've joined the list.
Do emphasize at the beginning of your text that people need to take action to be subscribed — if you bury that fact five paragraphs into the message, some people won't read that far. Some list administrators start the text with capital letters saying something like:
DO NOT IGNORE THIS MESSAGE IF YOU WANT TO BE ADDED TO THE SPRINGFIELD SCHOOL BOARD MAILING LIST!
We don't include anything that dramatic by default because some people would object to that "tone", but feel free to use it yourself if you think it's appropriate.