Webhost SMTP inaccessible after Bellsouth DSL DNS issue

[BlueWeasel]

Bellsouth had a massive outage beginning on Monday, as the DNS servers either crashed or were taken offline. Switching to alternate DNS servers like Verizon or OpenDNS worked fine.

Our DSL service is back up and Bellsouth's DNS servers (while crappy) appear to be working fine.

We have webhosting through Knownhost. However, we can't send email via SMTP. POP3 works fine, cPanel access works fine, and we can reach our homepage.

How would the DNS outage affect the SMTP servers days later? Bellsouth support claims the problem is not on their end, but they are idiots. I can't submit a ticket to Knownhost for some reason, and their forums aren't very active.

Prior to Monday, SMTP worked great. It's now 2 days after the DNS were restored and it's still not working. No settings were changed.

Any ideas? I'm lost at this point.

 

[Crusty]

They might be restricting SMTP traffic to ONLY their servers. Can you try pinging and doing a traceroute to the SMTP server at Knownhost?

edit: It could be that the DNS records at your ISP are wrong too. Should see what IP the smtp server resolves to on the Bellsouth DNS servers, and then change to a different DNS server and see what IP you are getting.

 

[RebateMonger]

Is DNS working at all? Does it work for sites other than the public DNS server that you use? Have you tried to Telnet to that DNS Server ( Telnet xxx.xxx.xxx.xxx 53) to see if there's a DNS server at that IP address?

Also, after looking up the name of your SMTP server, try to Telnet it, on TCP Port 25, too. You can try it both by name and by IP address (Telnet xxx.xxx.xxx.xxx 25, Telnet smtp.mydomain.com 25)

If you have your own internal DNS server, then consider using Root Hints for it, instead of a named external DNS server. That way, next time your ISP's DNS server crashes, it won't affect you directly.

Finally, make sure that ALL your DNS caches are flushed.