Knute Johnson wrote:
I'm running a FC5 box and using sendmail for my mail server. A
couple of days ago I noticed some mail not leaving and reporting
deferred because of No route to host. I tried to telnet to these
mail servers and get the same no route to host error. So it seems
that they are in fact not reachable. The odd thing is that they
should be busy mail sites. One of them is my own ISP's mail server.
Any
idea where to start looking for the problem?
Can you reach any external mail sites? If not the problem might be your
ISP or firewall has blocked any traffic from port 25.
If you can, figure out if the problem belongs to port 25 or is
reachability in general. Can you ping the external IP? Use traceroute
to the external site to see how far you can get with UDP if anywhere.
If that's fine, try telnet to port 80 on the same IP.
One other thing, the box at whatever.com might not handle the mail sent
to somewhere@xxxxxxxxxxxxx Use
$ dig whatever.com mx
and look for the line with MX in to find out where mail does go for that
domain and telnet to that box.
-Andy
