A
"hop" is the transmittal of a mail
message from one machine to another. Many such hops can be required
to deliver a message. The number of hops (the hop count) is
determined by counting the number of
Received: header lines
in the header portion of an email message. The maximum number of
allowable hops is compiled in for most versions of
sendmail but is set by the
MaxHopCount option with V8. When the hop count for
a message exceeds the limit set by the MaxHopCount
option (MaxHopCount), the message is bounced.
Ordinarily, the count begins at zero. The -h
command-line switch is used to specify a beginning hop count.
The forms for the -h command-line switch are:
-hnum
-h num
Space between the -h and
num is optional. If
num is missing,
sendmail prints the following error message and
ignores that switch:
sendmail: option requires an argument -- h
If num begins with a character other than
a digit, the offending text is printed:
Bad hop count (bad text)
The previous failure illustrates that the minimum hop count must be
positive.
The -h switch was originally used by BerkNet to
carry the hop count in the envelope. It currently has no application.
