[PLUG] SMTP monitoring

[Steve Bonds]

On Mon, 25 Oct 2004 15:39:54 -0700, Colin Kuskie wrote:

> When you get a bounce message and it says:
> 
> <user at remote_spot.org>... Deferred: Connection refused by server.remote_spot.org.
> 
> What does that mean?

A lot of things have to work correctly to get this message.  DNS
properly looked up server.remote_spot.org.  The first packet in your
attempt to set up a TCP connection to port 25 (SMTP) made it to the
remote server through any firewalls or flaky connections along the
way.  The remote server is up and sent you a packet back letting you
know that there was nothing for you to connect with on that port.

Usually "connection refused" means that there is no software (mail
server) up on the remote side, however it could also be due to a
firewall someplace.  Some ISPs may block outgoing E-mail with
"connection refused" in order to keep the spam-bot virus-infested
masses in check.  However, this should show up for all mail
destinations, not just one remote server.

If it's just the one remote server, it's probably their fault...

  -- Steve