Resolving the issue: 5.3.4 Message size exceeds fixed maximum message size
We recently discovered that several emails, we were expecting, were being rejected by our Exchange Server 2007 and giving the following basic response:
SMTP command failed when talking to server.domain.com: <<< MAIL FROM:host@remotedomain.com SIZE=16164910
>>> 552 5.3.4 Message size exceeds fixed maximum message size