To ensure that your mailing lists are not open to anyone, including spammers, who decide to post to them, Mailhandler provides three authentication methods. In the basic setup we chose From address authentication. Mailhandler matches the From address on the incoming message to a user account and verifies that the person with that email address has permission to post to the group.

Out of the box, Drupal keys each user account to a single, unique email address. In reality, many users have more than one email account, one for personal use; another at work; perhaps a third attached to a cell phone. When they post to a mailing list or comment on a post they don't want to have to think whether they're using the one account associated with the user email on your website. And you don't want them to create multiple user accounts on your site, one for each email address.

The solution is the Multiple Email Addresses module, which allows users to associate more than one address with a user account. If you've used Mailhandler in the past, you may have installed Mailalias to solve this problem, but it has been depricated. Mailhandler 6.x-2.x, under Mailhandler Extras on the Modules list, now includes a module to allow authentication using Multiple Emal Addresses.

1. Install and activate Multiple Email Addresses and the Mailhandler authentication plugin.
2. Go to admin/settings/multiple-email.
3. Adjust the settings to suit your site's needs.
4. Make sure the ability to add email addresses is visible to users when they edit their user account pages.
5. Go to the feed processor for your mailing list and click the IMAP Stream Processor Settings link.
6. In the Authentication plugin dropdown select Multiple Email authentication.
7. Click Save.
8. Make a similar change in the Listmaster feed processor.