Hi all!
I am new to the TechNET forums so apologies if this has already been asked, but it's quite a weird issue - and hoping some SMTP elites out there might be able to assist me.
I work for a company who is having issues receiving email from a particular sender.
From our side, when checking our server logs, we see the following:
2014-07-24 00:50:08.941966500 26010338: > MAIL FROM: <****@****.com>
2014-07-24 00:50:08.944333500 26010338: < 250 OK
2014-07-24 00:50:09.228785500 26010338: > RCPT TO: <****@****.com>
2014-07-24 00:50:09.248931500 26010338: - Using filter 'Brightmail' for recipient
2014-07-24 00:50:09.258600500 26010338: < 250 OK
2014-07-24 00:50:09.543366500 26010338: > DATA
2014-07-24 00:50:09.543368500 26010338: < 354 go ahead
2014-07-24 00:54:15.328082500 26010338: < 451 timeout (#4.4.2)
2014-07-24 00:54:17.253455500 26010338: *** session end ***
Our server times out if we receive no data from the sending server for a period of 4 minutes after we issue the 354 go ahead statement.
Generally this is quite cut and dry, however from the sender's side they are seeing this:
This is something I have never seen before, the 354 go ahead message is received from us by the sending server, they then appear to start to send the message, but immediately receive a blank response (from somewhere!).
I am at a loss as to where this empty response is coming from - we have no issues with any of our other clients delivering mail through to our servers, and any restrictions we have in place occur before the SMTP conversation starts.
Have any of you ever seen this in logs before where a blank message is received? I am convinced it's not our server generating this - but I am unable to provide any hard evidence to convince the sender of this.
Any help would be greatly appreciated.
Many thanks
YoyoLuke