Home > Bounce message

One reason that mail can bounce is if the recipient address is misspelled, or simply does not exist on the receiving system. This is a user unknown condition. Other reasons include resource exhaustion — such as a full disk — or the rejection of the message due to spam filters.

Bounce messages in SMTP are sent with the envelope sender address <>, known as the null sender address. They are frequently sent with a From: header address of MAILER-DAEMON at the recipient site.

Typically, a bounce message will contain several pieces of information to help the original sender in understanding the reason his message was not delivered:

• The date and time the message was bounced,
• The identity of the mail server that bounced it,
• The reason that it was bounced (e.g. user unknown),
• The headers of the bounced message, and
• Some or all of the content of the bounced message.