What Happens to Bad Mail Addresses?

> I was wondering what ListManager does with bad email
> addresses (e.g., addresses that do not exist, etc.)

If ListManager is unable to send mail to an address after all its retry attempts it increments the person's bounce count by one. Once the number reaches the value set in the List Settings screen, then that person is put on hold and mail will not be sent to them until they are unheld. Depending on how your list is set up, held users may or may not be deleted after a specified length of time. You also have the option of periodically notifying users who are on hold to give them the opportunity to unhold themselves. This is in the "List Settings."

Often, email addresses are not permanently bad. For example, juno.com sometimes has "mail quota exceeded" and bounces mail. But when the user clears their mailbox they are able to receive mail again. So they may not reach the criteria of bounce count and are not held. This is the reason why ListManager may take several days of bounces before holding people since many mail problems are temporary.