If you're running a discussion list, some of your subscribers may want to be able to post to the list from more than one email address, without getting copies of the list messages at multiple addresses. In that case, you or your subscriber can set up an "alternate" address. An alternate address is treated like a subscriber's address when confirming if a message should be sent to the list, but does not receive copies of list messages. Additionally, alternate addresses are unsubscribed when the subscriber leaves the list.
To set up an alternate address, there are three options:
Send the subscriber to the Subscriber Settings. Once they log in, they can create their own alternate address under "Alternate Addresses".
You can look up the subscriber on your Subscriber List. Click on their email address. At the bottom of the Edit Subscriber page, you can add an alternate address under "Alternate Posting Addresses".
If a large number of your subscribers have alternate addresses, you may find it easier to update them by Importing a Subscriber File. Just set up an Excel file with two columns, email_address and alternate_address, or add alternate_address as an additional column to your regular import file. Fill in the address they are currently subscribed under as email_address, and their alternate address as alternate_address. When previewing your import, please make sure that the correct field is listed as Primary Email Address and Alternate Email Address.