On Thu, 20 Apr 2000, Sylvain Lapointe wrote to
> I am managing different mailing lists for the two last years and
> recently (2 weeks ago) I began to receive some messages back sent to a
> mailing list with this mention :
> 554 hop-count exceed.
> What does it means exactly? What is a hop in an Email system?
The "hop-count" refers to the number of mail servers a message passes
through on its way from sender to destination. If you count the
"Received:" lines in the header of any message you receive, you can see
how many hops it took for that message to reach you.
Most mail trasnsport agents (sendmail, etc) can be configured to reject a
message if the hop-count reaches some configured maximum (typically about
15 hops). This is done primarily to break forwarding loops, where
email@example.com is set to forward to firstname.lastname@example.org and email@example.com is set to
forward to firstname.lastname@example.org. Without a hop count limit that would result in
messages forwarding endlessly back and forth between the two addresses.
There are other misconfigurations that can cause looping, but that's the
If you get a "hop-count exceeded" error, examine the "Received:" lines to
see where the loop is. Either unsubscribe the offending address from your
list, or find some non-email way to get in touch with the addressee or his
local postmaster and get the problem fixed.
Chip Old (Francis E. Old) E-Mail: email@example.com
Manager, BCPL Network Services Voice: 410-887-6180
Manager, BCPL.NET Internet Services FAX: 410-887-2091
320 York Road
Towson, Maryland 21204 U.S.A.