[Exim] Incomplete transactions

Over the past week I have been getting ALOT of calls of clients trying
to send e-mail to our SMTP servers, which are both running the same
configuration, that the connection to the SMTP server is timing out. I
the logs on our side, we are seeing the error of 'incomplete transaction
(RSET)' on SOME of them. I really have not found a good reason why this
is occuring, so obviously I can not figure out how to correct this. I
know that this probably can be caused by a wealth of different things,
but the strange thing is it is not happening to everyone, and not even
in specific areas. Please let me know your thought on what might be
causing this. I know I have not included much specific information,
because I really do not know what to include. All I do know is I have
to get this resolved quickly, I have lost at least 30-40 users this week
because of this specific problem. Thanks in advance.

Stephen