TomB

Member
Sep 3, 2002
19
0
151
The problem started a couple of months ago. First I had reports from customers, not receiving mail sent from cox.net. I was able to get that working by going to, Service Configuration > Exim Configuration Editor > and checking the "Use callouts to verify the existence of email senders". Now, I'am getting reports that customers using my server for smtp can't send to cox.net customers. Has anyone else experienced this? Cox, I might add is of no help in resolving this. Thanks in advance for any insights you might provide.
 

ckh

Well-Known Member
Dec 6, 2003
358
1
168
Phoenix, AZ
cPanel Access Level
DataCenter Provider
I've been with cox about 10 years now. Here's some of my observations:

1) They implemented blocking both ports 25 and 26 quite a while ago. Luckily, I run my own servers so I simply set up Exim to run on port 27. :D

2) They have intermittant periods where the email is delayed. I've seen it very from an hour to a few days. It seems to always get delivered but there are times it's delayed for unknown reasons.

3) Probably in the last 3 or 4 months, I noticed that they started using some blacklists. Notedly, surbl. If you have a URL in the email that is listed in the surbl then it will be rejected. This can be in the signature line also.

To determine why it's being blocked, you need review your mail logs to see why it's being rejected. I try to get customers to forward a bounce to me. If rejected because of the surbl, it's being scanned before the message is accepted and will be rejected immediately. Clients may get a popup stating it was rejected.
 

TomB

Member
Sep 3, 2002
19
0
151
Thanks for the reply. I too, have configured Exim to use port 27 and can send mail using my server while connected to the cox network. However, I use the cox smtp server most of the time. My server nor the IP is listed on any SURBL list. I've tested with Spamassassin both enabled and disabled. The funny thing is I'm not getting any reject or returns on mail sent to cox.net .. the mail is just not getting through. Thanks for your input.
 

Spiral

BANNED
Jun 24, 2005
2,020
8
193
Do you have SPF for the domains and reverse DNS setup on your mail server IP?
 

markfrompf

Well-Known Member
Mar 27, 2006
176
0
166
Los Angeles, CA

TomB

Member
Sep 3, 2002
19
0
151
Thanks Mark. Let me ask you this. Since there is one reseller on the server besides myself I have the server set up with "mydomain.com" as one reseller (me) and "myreseller.com" set up as another. mydomain.com uses the primary IP and myreseller has a dedicated IP. Now the question is do I need to set the SPF up for me AND myreseller? And do ALL the domains being hosted on the server either by me or my reseller ALSO need to have SPF added to their individual zone files? Thanks again for your help.