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On Monday 03 Feb 2003 6:47 pm, Jeff Hutchinson wrote:
> I have setup an email server which stands behind a firewall. Internally
> we are able to sent and receive email. I fact we can send email
> anywhere. The problem lies with the incoming email --- none.
Obvious first question - does your primary MX point to the A record for the
mail server, or are there no MX records and just an A record (either should
work, but an MX record is always good just for luck). Then, if mail is sent
to other MX's, do those have the correct rules to forward onto you ?
Also, does the firewall log any attempted inbound SMTP connections, successful
or not ? If it's not configured to, then set it to do so so you'll have
some idea of there are any incoming packets.
If you can't do that do:
tcpdump -n port 25
on the mailhost to watch SMTP transactions.
> I have checked the following,
>
> 1. Allowed port 110/tcp and 25/tcp through the firewall. From outside
> the firewall you can telnet to the server and it responds.
OK, so if no mail is getting to you then it's highly likely it's a DNS issue.
Check:
1) The MX record for the domain points to an address record for the mail
server. It must *not* point to a CNAME and it must *not* be an IP address.
i.e. mydomain.org.au IN MX 5 mailhost.mydomain.org.au
mailhost.mydomain.org.au IN A 10.1.1.1
2) Confirm that from a third party such as http://www.samspade.org/t/
3) Use tcpdump (as above) to confirm incoming packets.
4) From the outside send an email using telnet to port 25.
> 2. I'm fairly sure DNS is working but I have the FEATURE( accept_
> unresolved_domains) turned on ( not my favorite option ).
>
> I have attached part of the maillog.
> The system is Redhat 8.
Erm, that log file only had POP traffic, no sendmail log entries at all.
- --
Chris Samuel Wollongong, NSW
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