Knowledgebase: SMTP Server (Outgoing)
What does
Posted by Roy Petersen on Feb-15-2007 12:16 PM
This message is sent back to you, the sender, from the SMTP (Simple Mail Transfer Protocol) server. That server is telling you that the "user" you tried to send e-mail to doesn't exist. The user (user@domain.com) may have existed at some point in the past, but is no longer available.

As people open and remove e-mail addresses, this will sometimes happen. Once removed from the system on which they previously had an e-mail account, all e-mail sent to them will be refused and bounce back.

An example would be if you sent e-mail to baduser@woollybear.com. Since we have no user setup under the login "baduser", the e-mail will bounce back immediately. In order to correct this problem, you will need to contact the recipient through other means and obtain their new e-mail address.