When we send emails over about 15 MB in size to other Exchange servers in our system, or to an external email provider, we sometimes see this error---
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Remote Server at ------ returned'400 4.4.7 Message delayed'
3/23/2016 11:08:41 PM - Remote Server at ------ returned
'451 4.4.0 SMTPSEND.SuspiciousRemoteServerError;
remote server disconnected abruptly; retry will be delayed'
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We have checked many network settings (based on information in various forum items about this error), and we think that is not the problem.
This only happens at one of our Exchange locations.
The other locations can send emails of 25 MB and they are delivered correctly / no errors.
The ping time from the location sending emails, to the Exchange location receiving emails, is 430 ms.
That connection is over the Internet with a VPN.
It seems like Exchange thinks this is taking too long, or too many attempts, or something like that.
(Since somewhat smaller emails are delivered OK.)
Is there an Exchange configuration parameter in Transport service or similar, that we can change, to tell Exchange to "wait a little longer", before issuing that error ?
Thanks
Exchange 2013 CU10, Windows server 2012 Standard, Outlook 2013,
SMTP,
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