sendmail, 4th Edition

Date and Trace Headers

Date headers are used to document the date and time that the mail message was sent or forwarded. Trace headers (those with an H_TRACE header flag; H_TRACE Header Flag (V5 and Later) on page 1142) are used to determine the hop count of a mail message and to document the message’s travel from machine to machine. The list date and trace headers are shown in Table 25-9.

Table 25-9. Date and trace headers

Header	§	Flags	Defined by
Date:	Date: on page 1155	None	RFC2822
Posted-Date:	Posted-Date: on page 1161	n/a	Obsolete
Resent-Date:	Forwarding with Re-Sent Headers on page 1147	H_RESENT	RFC2822
Received:	Received: on page 1162	H_TRACE, H_FORCE	RFC2822
Via:	Via: on page 1167	H_TRACE, H_FORCE	Obsolete
Mail-From:	Mail-From: on page 1159	H_TRACE, H_FORCE	Obsolete
X-Authentication-Warning:	X-Authentication-Warning: on page 1167	H_FORCE	V8 sendmail
X400-Received:	X400-Received: on page 1168	H_TRACE, H_FORCE	IDA and V8 only