Qmail Not sending

[ChildOTK]

Hi All,

I am having an issue with our outgoing email.

A couple of months ago we got a new server and we migrated from a plesk server to another plesk server. Everything in theory is the same, apart from the new server and different OS. We went from RHEL4 to CentOS 5.

I have right now about 450 email's in the que, but they are mostly bouncing back with the following errors:

deferral: Sorry,_I_wasn't_able_to_establish_an_SMTP_connection._(#4.4.1)

OR

deferral: Connected_to_x.x.x.x_but_connection_died._(#4.4.2)

I am really struggling here to find out what the exact problem is.

If anybody can help it will be appreciated.

This does not happen to all our email, but it is happening to a huge amount of them.

Thanks,
Regards,
ChildOTK

 

[atomicturtle]

that could mean they're filtering out your IP. Id try telneting to the smtp ports on those systems that you cant connect to.

 

[ChildOTK]

Ok, I just tried that...

I am able to telnet in via port 25. Is there another port you may suggest?

 

[atomicturtle]

Nope, sounds like a networking issue. Id talk to your ISP about it

 

[ChildOTK]

Alright, thanks.

I have spoken to our hosting company about this (we have a managed dedicated server with them), but they have not gotten back to me yet.

Our server with them is in LA, but our campus is in Dallas. So all our email originates from our campus IP address and not our hosted server in LA.

Something wierd though. It seems to happen to on a lot of the same domains. For example with Yahoo.com and Hotmail.com, and then a few others.

I had sent an email to my personal yahoo.com account, and the email was not yet recieved, but once I sent an email from yahoo.com to our own domain, and then back again, that seemed to have solved the issue with the Yahoo.com domain, and I received the first email I had sent to test with.

I have done further checks to see if our IP is possibly blacklisted, but on all sites I check I come back not being in their blacklist.

We did however have a huge problem on our campus (Which serves roughly 1000 computers which all go through 1 public IP address), and we got blacklisted 3 times in the space of 5 days. It turned out to be a spam virus which we located on two different machines, and have solved that issue. I did request delisting and since then we have not been blacklisted again.

Do you think this could perhaps be related?