Sendmail Installation and Operation Guide
SMM:08-93
H_EOH
If this header field is set, treat it like a blank line, i.e., it will signal the end
of the header and the beginning of the message text.
H_FORCE
Add this header entry even if one existed in the message before. If a
header entry does not have this bit set, sendmail will not add another
header line if a header line of this name already existed. This would nor-
mally be used to stamp the message by everyone who handled it.
H_TRACE
If set, this is a timestamp (trace) field. If the number of trace fields in a
message exceeds a preset amount the message is returned on the assump-
tion that it has an aliasing loop.
H_RCPT
If set, this field contains recipient addresses. This is used by the -t flag to
determine who to send to when it is collecting recipients from the mes-
sage.
H_FROM
This flag indicates that this field specifies a sender. The order of these
fields in the HdrInfo table specifies sendmail's preference for which field
to return error messages to.
H_ERRORSTO
Addresses in this header should receive error messages.
H_CTE
This header is a Content-Transfer-Encoding header.
H_CTYPE
This header is a Content-Type header.
H_STRIPVAL
Strip the value from the header (for Bcc:).
Let's look at a sample HdrInfo specification:
struct hdrinfo
HdrInfo[] =
{
/* originator fields, most to least significant */
"resent-sender", H_FROM,
"resent-from", H_FROM,
"sender", H_FROM,
"from", H_FROM,
"full-name", H_ACHECK,
"errors-to",
H_FROM | H_ERRORSTO,
/* destination fields */
"to", H_RCPT,
"resent-to", H_RCPT,
"cc", H_RCPT,
"bcc", H_RCPT|H_STRIPVAL,
/* message identification and control */
"message", H_EOH,
"text", H_EOH,
/* trace fields */
"received",
H_TRACE | H_FORCE,
/* miscellaneous fields */
"content-transfer-encoding", H_CTE,
"content-type", H_CTYPE,
NULL, 0,
};
This structure indicates that the "To:", "Resent-To:", and "Cc:" fields all specify recipient
addresses. Any "Full-Name:" field will be deleted unless the required mailer flag (indicated in
the configuration file) is specified. The "Message:" and "Text:" fields will terminate the header;
these are used by random dissenters around the network world. The "Received:" field will