The Reply-To: header requests that replies to messages go to an address that is different from that of the original sender. This header is usually inserted by mailing-list software, where the From: is the address of the author of the message and the Reply-To: is the address of the list.

The field for the Reply-To: header must obey the same rules as those for the From: header's field. One example of the use of this header might look like this:

From: bob@list.server.domain
Reply-To: mailinglist@list.server.domain

The Reply-To: header should never be declared in the configuration file.