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All of a sudden I stopped recieving emails from certain domains

Posted on 2015-01-13
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All of a sudden I stopped receiving emails from certain domains.  I can send to these domains, but not receive.  A big one I can't receive from is gmail.  I do an MX and DNS record check everything comes up fine.  Nothing has changed on the network.  The email is not even hitting my Astaro, which is what I use for email filtering, then is forwarded to exchange.  The Astaro is my MX record.  So the emails from gmail for example are not even hitting my network, and the gmail users have yet to get any kick back to even help troubleshoot the problem.  I also have a few other domains that I can't receive email from.  For the most part though we are getting all our email from other domains.  This started yesterday.
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Question by:denver218
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Jessie Gill, CISSP earned 1000 total points
ID: 40547569
Has your public IP used for MX recored changed?
Also have you checked if your ISP has blocked SMTP traffic,
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by:denver218
ID: 40547579
nope.  nothing at all has changed.  If you do a MX record and dns check all is fine.
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by:Jessie Gill, CISSP
ID: 40547587
if they are not even hitting your mail gateway, could thier be an issue with your ISP, are they having some issues?
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by:Jessie Gill, CISSP
ID: 40547588
I would send an email from gmail to your Email on exchagne and see if you get a bounce back
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by:Don S.
Don S. earned 1000 total points
ID: 40547593
The other domains may in fact be using gmail servers to send mail.  It's possible that the incoming mail connection is being rejected immediately at your spam filter - possibly because of the sender being on an RBL or something like that.  The rejections may not make it back to the users for a while if ever.  Gmail can be a tough one to figure out once someone is on someone else's naughty list.
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by:denver218
ID: 40547614
I called the ISP, and am waiting on a call back.  If I send a test email from gmail, I don't get any kind of kick back, nor is it even hitting my Astaro (email gateway).  Yes it is possible the other domains are using gmails servers.
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by:Jessie Gill, CISSP
ID: 40547679
ok that means, that Gmail is attempting to deliver the message, it will try a number of times before any NDR comes back. The fact that you indicated that email is not even reaching your gateway appliance, seems to indicate a communication problem from Gmail to you server. Most likely the ISP is having issues, or Gmail could have issues.
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by:Bahloul
ID: 40548334
if you have anti-spam or anti-virus could prevent some message.


Bahloul
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by:denver218
ID: 40549208
So it was a bug in our email gateway (Sophos UTM 220).  They released bad firmware.  Everyone who uses a Sophos UTM, running 9-210 code were affected.  The SMTP logs didn't even show these emails were being rejected, which made it very difficult to troubleshoot, especially since we were not getting any NDR.  I called Sophos in desperation as I couldn't think what else it could be, and after a 2 hours of listening to their hold music, I finally got through to someone and they said it was a bug, and they were able to fix it.
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Author Closing Comment

by:denver218
ID: 40549213
Thanks for all your help.  As I stated in the last post, it was bad firmware in the Email Gateway.
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