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SBS 2011:  Exchange 2010 server on email blacklist

Posted on 2013-06-27
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904 Views
Last Modified: 2013-07-03
Hi All,

A customer recently rang to say their emails arent all being sent.  On investigation they are on an emai lblacklist.

I've put a request in to have it removed.  But need help to find out why?

Also, how do I find out how many emails have been sent today?

The Queue only has 15 emails waiting, which are all because of the blacklist.

Any suggestions?

D
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Question by:detox1978
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12 Comments
 
LVL 8

Assisted Solution

by:s3e3
s3e3 earned 100 total points
ID: 39282372
The blacklist provider will usually tell you why it was blacklisted.
Open relay is common, check your server's smtp by using the tools on dnsstuff.com

It's hard to tell how many outbound emails are blocked because some receiving servers do not use IP block lists or have less aggressive spam filtering.
If outbound emails are blocked users will get a message on most occasions.
0
 
LVL 2

Author Comment

by:detox1978
ID: 39282434
The blacklist company have whitelisted them for 30 days as it's the first time they've appeared on the list.  But it was an automated system that sent a generic email.  You "may" have a virus etc....
0
 
LVL 76

Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 400 total points
ID: 39282512
Which Blacklist(s) did they appear on?

Is port 25 outbound closed off on the firewall from all LAN IPs apart from the SBS 2011 server's IP?  If not - it needs to be.
0
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LVL 2

Author Comment

by:detox1978
ID: 39282593
at the moment there is no ports blocked on the lan and the exchange server accepts from all sources.

Open relay isnt enabled.
0
 
LVL 76

Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 400 total points
ID: 39282599
You should be blocking port 25 outbound for all LAN IP's other than the Exchange server or a virus infected PC will get you blacklisted because you haven't blocked it from sending spam out.

Chances are you have an infected computer and that is why you got blacklisted.

Which Blacklist did you hit?????
0
 
LVL 2

Author Comment

by:detox1978
ID: 39282752
They were on BARRACUDA's blacklist
0
 
LVL 76

Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 400 total points
ID: 39282800
Okay - so that would be most likely down to a virus infected computer.

Did you check for Open Relay on your server on http://www.mailradar.com/openrelay/ ?
0
 
LVL 2

Author Comment

by:detox1978
ID: 39283088
Thanks for the tips.

Server passed the open relay checks and i've restricted port 25 to the SMTP server.

Are there any checks I can do on the server.  As they were only on one blacklist i'm starting to think they havent done anything to be on there.
0
 
LVL 76

Accepted Solution

by:
Alan Hardisty earned 400 total points
ID: 39283180
An outbreak would usually mean you end up on several lists, so they may have been inadvertently listed.

Did you check when the last listing was?  Was it recently?
0
 
LVL 2

Author Comment

by:detox1978
ID: 39283199
They noticed some email stopped being sent around 2pm BST and that they were on a blacklist around 4pm.  They applied to be removed around 6pm and were removed soon after.

All emails are working now, but I was hoping to find out how/why they got on the list in the first place.
0
 
LVL 76

Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 400 total points
ID: 39283206
If you can log activity on your firewall then log port 25 activity that is blocked and that may tell you where the problem lies, otherwise you may never know.
0
 
LVL 2

Author Closing Comment

by:detox1978
ID: 39297916
thanks
0

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