[Exim] Multiple deliveries

Hi all, I am getting the occasional reports from users about multiple
deliveries. We are exim 4.24.

It only happens rarely and then only to off campus addresses. Is it
possible there is some timing issue, where exim sends the message and
does not get an ack in time so sends it again. I am afraid I don't know
what MTA is at the other end. If any of you have seen this before or
have any ideas I would be grateful.

Ron
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Ron McKeating
Senior IT Services Specialist
Internet Services and Software Solutions
Loughborough University
01509 222329