Identification and Control Headers

Some headers serve to uniquely identify a mail message. Others affect the way sendmail processes a mail message. The complete list of all such identification and control headers is shown in Table 25-8.

Table 25-8. Identification and control headers

Header

§

Flags

Defined by

Message-ID:

Message-ID: on page 1159

None

RFC2822

Resent-Message-Id:

Forwarding with Re-Sent Headers on page 1147

H_RESENT

RFC2822

Message:

Message: on page 1160

H_EOH

Obsolete

Text:

Text: on page 1167

H_EOH

Obsolete

Precedence:

Precedence on page 1148

n/a

All sendmails

Priority:

Priority: on page 1161

n/a

Many (maps to X.400)

Note that the Precedence: and Posted-Date: headers (discussed next) are hardcoded into sendmail rather than being declared in conf.c.

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