Connection reset

If you haven't already checked, see if your ip is not blacklisted

[link]http://www.anti-abuse.org/multi-rbl-check/[/link]

mwanza_k wrote:

Hi good people

 

I have been struggling with this error "Stat=Deferred: Connection reset by *****.com (Reason:451 4.4.1 reply: read error from *****.com)" for quite sometime, unit is FortiMail VM08, note this only happens when i send to certain domains, any help with this will be greatly appreciated.

4xx error code are designed for temporary errors

Maybe is only greylisting feature enabled and not a 'problem'

You should check your logs deeply; use cross  search feature with right button over specific log line.