Set up your Mailman list as a newsletter

Mailman is setup by default to be used as a discussion list. However, it can be set to be used as a newsletter.
Make a note in your list info page and in the header that this list functions only as a newsletter.
Under General Options, you need to set it so that replies to posts are sent to the poster.
Under Privacy Options, you should set it so that administrative approval is necessary for posts.

Add a member to your list

Aside from the user subscribing themselves, you are also able to add people to your list.

Access your Mailman Admin section.
In the Membership Management section, scroll down to the area labeled "Mass Subscribe Users."
Type the address of the individual that you would like to add into the text box. If you would like to add more than one person, enter each address on a separate line.
If you would like to send a welcome message to the new members then make sure that the "yes" button is checked. This will send the new members their password and list configuration instructions.
Click the "Submit your changes" button at the bottom of the screen to put the changes into effect.

Note: Network etiquette generally frowns on opt-out lists -- adding unsuspecting persons to a list and then telling them that they can leave if they want. Do not use Mailman for activities such as sending Spam, which may result in the termination of your account.

Removing a user from a list

You can also directly remove an individual from your list.

Access your Mailman Admin section.
In the Membership Management section, find the line with the e-mail address of the individual that you would like to remove.
The check mark in the first column by their address, labeled "subscr" indicates that they are subscribed to your list. Uncheck the box by the address that you would like to remove.
Click the "Submit your changes" button at the bottom of the screen to put the changes into effect.

Keep unwanted persons from joining

You are able to prevent people from joining your list without your explicit approval. To activate this feature:

Access your Mailman Admin section.
In the Privacy Options section look at the second field, labeled "what steps are required for subscription."
Set the option to "require approval" or "confirm+approval" and click the "Submit your changes" button at the bottom of the screen.

Future subscription requests will cause Mailman to send you an e-mail message telling you that someone has tried to join your list. Go to the URL in the message and then use the on-screen form to accept or reject their request.

Changing maximum message size

Mailman places a limit on the size of message that it will deliver to prevent large messages from disrupting the list server of user mailboxes. In some cases the default value may not be large enough to allow messages and file attachments to pass through in a manner suitable for your list's purpose. To change the limit:

Access your Mailman Admin Section.
In the General Options section, near the bottom, locate the field for "Maximum length in Kb of a message body" field. Change the limit to something suitable, or enter 0 for no size limit.
Click the "Submit your changes" button at the bottom of the screen to put the changes into effect.