sendmail, 4th Edition

Sender Headers

Certain header names are assumed by sendmail to contain information about the various possible senders of a mail message. They are listed in Table 25-6 in descending order of significance. Addresses with the H_FROM flag (H_FROM Header Flag (V5 and Later) on page 1141) are rewritten as sender addresses.

Table 25-6. Sender headers (most to least significant)

Header	§	Flags	Defined by
Resent-Sender:	Forwarding with Re-Sent Headers on page 1147	H_FROM, H_RESENT	RFC2822
Resent-From:	From: on page 1157	H_FROM, H_RESENT	RFC2822
Resent-Reply-To:	Forwarding with Re-Sent Headers on page 1147	H_FROM, H_RESENT	RFC2822
Sender:	Sender: on page 1166	H_FROM	RFC2822
From:	From: on page 1157	H_FROM	RFC2822
Apparently-From:	Apparently-From: on page 1150	n/a	Smail 3.0
Reply-To:	Reply-To: on page 1164	H_FROM	RFC2822
Disposition-Notification-To:	Disposition-Notification-To: on page 1156	H_FROM	RFC2298
Return-Receipt-To:	Return-Receipt-To: on page 1165	H_RECEIPTTO	Obsolete
Errors-To:	Errors-To: on page 1156	H_FROM, H_ERRORSTO	sendmail (deprecated)
Full-Name:	Full-Name: on page 1158	H_ACHECK	UUCP (obsolete)

When returning bounced mail, sendmail always uses the envelope sender’s address. If the special header Errors-To: appears in the message, and if the UseErrorsTo option (UseErrorsTo on page 1115) is set, a copy of the bounced mail is also sent to the address in that header.