Incoming email being dropped inconsistent


Mar 14, 2005
I've been looking through the forums and haven't found the answer for this but maybe someone has it...

My server is

WHM 10.0.0 cPanel 10.0.0-R146
Fedora i686 - WHM X v3.1.0

What is happening is that some incoming email is being dropped and some is getting through. I've sent test messages from and found that if there is no attachments or small ones they are delivered instantly but if the attachment is larger, say 1mb. The message seems to disappear.

I have complaints from customers that messages are being delivered days after being sent from an external email system or getting returned after a few days.

If I sent a test message to [email protected] the automatic response never is received. The same test from a and yahoo account gets the response message.

Where do I start with this?


Well-Known Member
Verifed Vendor
Jun 15, 2002
Go on, have a guess
The starting point is your log files (Linux):


You should tail that while testing and look for errors.


1. Make sure that the servers main IP address has an rDNS PTR record setup by the netblock owner, i.e. that the following yields a result:

dig -x

(where is your main servers IP address)

2. Make sure that domains are resolving correctly with the information in your /etc/resolv.conf

3. Are you running any add-on apps such as the exiscan patch, MailScanner or the clamavconnector? If the latter (clamavconnector) try removing it.

4. Do you have WHM > Exim Configuration Editor > Always set the Sender: header when the sender is changed from the actual sender > checked? If so, uncheck it as this is known to cause problems for some people.

5. Have you tried resetting your exim configuration back to defaults: