[ale] Blacklisted mail server?

[Nathan J. Underwood]

I thought to add reverse addresses for the primary and secondary MX's, 
but didn't add one for their gateway.  Although I don't know why that 
would make a difference, I'm adding one now (just in case).
--

registered linux user # 73046

Nathan J. Underwood
Proverbs 16:11

Joe Steele wrote:
> On Friday, March 18, 2005 2:54 PM, Nathan J. Underwood wrote:
> 
>>A client of mine has recently started using Cbeyond as their ISP.  Since
>>the cutover, they've had problems sending emails to random domains.
>>After digging around a bit, I've found that they seem to be blacklisted.
>>    The error messages that the users are getting were pretty generic,
>>so I started digging further.  My first move was to ping the server
>>reported as the primary MX for the recipient (got a response).  I then
>>tried to telnet to the mail server (i.e. telnet mail.server.net 25), and
>>got an immediate connection refused.  I then tried the same exercise
>>from my ip (not blacklisted), and was able to connect.  They're not an
>>open relay, and I've not been able to find any lists that their listed
>>on.  Anyone got any suggestions on where to look next?
> 
> 
> Just a guess:
> 
> I believe Cbeyond doesn't usually have reverse DNS set up for their 
> IP addresses.  Could it be that some mail servers are refusing the 
> connection because of this?  If so, then your client can probably 
> report the problem to Cbeyond and have them set up reverse DNS for 
> their IP(s).
> 
> --Joe
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