Weird sending email problems

griz

Well-Known Member
Dec 29, 2001
47
0
306
Hello,

I'm seeing a strange email problem with several clients on one of my servers this week.

It seems that some clients are suddenly not able to send email, though they can receive it just fine.

I know what you're thinking...ISP shut off port 25...right???

Nope.

I remoted onto these clients computers, verified they have port 26 entered on advanced tab, pulled up the dos prompt, and successfully used telnet domain.com 26 to log into my mail server. Slides right through like a hot knife through butter. Ports are wide open.

My next thought is that they don't have "My server requires authentication" checked. I check the settings, and they most certainly do.

Next, I remove the account out of their outlook express and re-create the account using correct settings. I close and re-open outlook express, and I still can't send.

Okay, here's where it gets weird... I set up their email account on my own office computer, and I'm able to send just fine.

I checked /etc/apf/deny_hosts.rules for their IP address, and I find nothing.

Anybody got a clue what might be going on?

Thanks in advance for your help.

Larry
 

pagchen

Member
Aug 19, 2007
8
0
51
Same problem here as well

I experience the same problem as well. I even checked to see if there provider was on RBL lists and they're not.

If I find anything, I'll let you know.
 

mtindor

Well-Known Member
Sep 14, 2004
1,363
65
178
inside a catfish
cPanel Access Level
Root Administrator
Did you check and see what kind of antivirus software they have installed? I can't think of an antivirus suite that works properly 100% of the time when it proxies the email through. So, I would tend to blame a firewall on the local computer or antivirus/security software installed on the client computer.

That is the only thing it _could_ be if you can telnet to your port 26 and get a banner AND you don't see any reference to the attempts to send in your Cpanel exim logs.

Mike
 

darren.nolan

Well-Known Member
Oct 4, 2007
259
0
66
If it's just them - you could easily consider it has nothing to do with your server, especially since you've checked out your IP deny list.

A short time ago, ZoneAlarm's firewall brought out an update which killed users internet. The fix gave users back web access, but still mucked up a lot of things such as emails and games. Perhaps something like this is occuring?

I know mail-scanners on the client end can also be full of fun to debug (norton's is normally the one that has it's "moments" where it stops emails as it's not able to scan them - for whatever reason).

But if all that stuff is turned off or you have checked it's not those things, well I have no clue.
 

sehh

Well-Known Member
Feb 11, 2006
579
5
168
Europe
I've had clients with similar problems and its always some stupid antivirus like Norton which hijacks the SMTP connection as a transparent proxy. Sometimes the antivirus crashes or freezes and as a result SMTP connections seem to connect (in reality they've only connected to 127.0.0.1) but no real outgoing connection is made.

Try to disable their antivirus or remove/disable email checking.
 

riteme

Registered
Jul 31, 2008
4
0
51
Email sending problems

If anyone uses AOL as their ISP then the problem with Port 26 is AOL. I talked with tech support there and for some reason they have Port 26 blocked. I was told they will see about removing the block.