[afnog] mail problem

[Brian Candler]

On Wed, Apr 19, 2006 at 08:41:02AM +0300, Mike Barnard wrote:
> 
>      Works from here:
>      $ telnet [1]mail.avsi.org 110
>      Trying 81.208.64.123...
>      Connected to [2]mail.avsi.org.
>      Escape character is '^]'.
>      +OK <[3]27456.1145391436 at avsi.org>
> 
>    Thanks Brian. been at it almost the whole of last night, bringing down
>    rule of the routers and trying but still no avail. if it was a routing
>    problem i should not be able to send  mail to them

No, this is not necessarily true.

What E-mail address exactly are you sending to? If it is foo at avsi.org, then
check the MX records:

$ nslookup -q=mx avsi.org.
...
avsi.org        mail exchanger = 30 mail2.avsi.org.
avsi.org        mail exchanger = 10 main.avsi.org.
avsi.org        mail exchanger = 20 mail.avsi.org.

You only need IP reachability to one of those three different mail servers
to be able to send mail to them. (Having said that, all are on the
81.208.64.* network, and two of them are the same machine anyway)

You can test like this:

# telnet mail.avsi.org. 25

and

# telnet mail2.avsi.org. 25

If you find that you can connect to mail2 but not mail, then there is a
routing problem between you and mail (or 'mail' has firewalling rules which
blocks out traffic from you, which amounts to the same thing)

If you find that you can connect to mail.avsi.org on port 25, but not on
port 110, then it's almost certainly a firewalling problem.

>    one_gate_rtr#ping [18]81.208.64.123
>    Type escape sequence to abort.
>    Sending 5, 100-byte ICMP Echos to [19]81.208.64.123, timeout is 2
>    seconds:
>    .....
>    Success rate is 0 percent (0/5)
>    one_gate_rtr#

I can't ping mail.avsi.org from here either. This says they have configured
packet filters blocking ICMP (which I consider to be poor practice, and
unless done *very* carefully it breaks important IP functions such as path
MTU discovery)

This suggests to me that it's their packet filters which are also blocking
you out.

Anyway, come back here with your results of connecting to mail/mail2 on port
25.

Regards,

Brian.