[BlueOnyx:22057] Sendmail and premature EOM

[Richard Morgan :: Morgan Web]

Hi, I'm getting a problem with my 5208R which is configured to only handle
secondary DNS and act as an outbound email relay.

Most email relayed is fine, but nearly all messages from a particular
site/client consistently fail. The log files are:

May 15 09:05:09 vps1 sendmail[32057]: w4F9567n032057: collect: premature
EOM: unexpected close
May 15 09:05:09 vps1 sendmail[32057]: w4F9567n032057: collect: unexpected
close on connection from [hostname], sender=<[sender email]>

The senders are using Outlook 2010 and there is no error, the message just
sit in the Outbox. Searching Google doesn't give any clear answer but people
suggest messing with MTU values which doesn't make a lot of sense.

I'm not totally convinced it's a BlueOnyx problem but if anyone has any
ideas how I can prove the source of the problem I would be really grateful
as I'm a bit stuck on a way forward.

cat /etc/build
build 20140909 for a 5208R in en_US

uname -a
Linux vps1.diamond-discovery.net 2.6.32-696.23.1.el6.x86_64 #1 SMP Tue Mar
13 17:46:31 CDT 2018 x86_64 x86_64 x86_64 GNU/Linux

There are no additional packages on this server as it's only got basic
roles.

Many thanks indeed, Richard