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Non existant email addresses sent to our domain.

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Non existant email addresses sent to our domain. - 18.Nov.2010 10:44:33 AM   
akersrus

 

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Joined: 18.Nov.2010
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Hi,

we are having trouble with receiving email to addresses that don't and never have existed to our domain. We would like to stop this somehow, but I don't think saying Please is going to help. An example of the addressed mail is "any old name under the sun@domain.com. We are not exchange experts, so we are really needing help understanding this and why it is happening.  We do see in the event log we are kicking out NDR's left and right. Can anyone explain this to me and what I can do about it?
Thank you in advance.
Post #: 1
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:03:06 AM   
alanhardisty

 

Posts: 389
Joined: 28.Feb.2010
Status: offline
You simply need to enable Recipient Filtering to prevent this which will reject any invalid emails sent to your server and then the sending server (spammer) will be responsible for producing a NDR report, not your server.

To learn how - please read the following link:

http://www.msexchange.org/tutorials/Sender-Recipient-Filtering.html

_____________________________

Alan Hardisty

http://www.it-eye.co.uk
http://alanhardisty.wordpress.com
http://www.exchange-certificates.com

(in reply to akersrus)
Post #: 2
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:05:16 AM   
alanhardisty

 

Posts: 389
Joined: 28.Feb.2010
Status: offline
You should also check on http://www.mxtoolbox.com/blacklists.aspx - enter your IP Address and make sure you are not Blacklisted.

You may have popped up on Backscatterer.org and once you have enabled Recipient Filtering, you can request de-listing from Backscatterer as you will no longer be sending out Backscatter (NDR's to Spammers).

_____________________________

Alan Hardisty

http://www.it-eye.co.uk
http://alanhardisty.wordpress.com
http://www.exchange-certificates.com

(in reply to akersrus)
Post #: 3
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:07:18 AM   
akersrus

 

Posts: 18
Joined: 18.Nov.2010
Status: offline
Thank you so much for your help, well do all that is suggested

(in reply to akersrus)
Post #: 4
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:09:01 AM   
alanhardisty

 

Posts: 389
Joined: 28.Feb.2010
Status: offline
No problems.

Once you have enabled Recipient Filtering - empty your queues that are not going anywhere too - then monitor to see if any new ones pop up.

You should be fine after doing this and making sure you are not Blacklisted.

If you need anything else - just post another comment.

_____________________________

Alan Hardisty

http://www.it-eye.co.uk
http://alanhardisty.wordpress.com
http://www.exchange-certificates.com

(in reply to akersrus)
Post #: 5
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:11:07 AM   
akersrus

 

Posts: 18
Joined: 18.Nov.2010
Status: offline
one more thing, what if these email's are coming from several different sources?
Will I need to enter each address?

(in reply to alanhardisty)
Post #: 6
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:17:22 AM   
alanhardisty

 

Posts: 389
Joined: 28.Feb.2010
Status: offline
You don't need to add email addresses - simply enable Recipient Filtering which tells Exchange to reject any email addresses that are not listed in Active Directory. That's it.

So when a new mail comes in from spammer1@spamdomain1.com to invalidrecipient1@yourdomain.com - Exchange will reject it and not send an NDR message.

_____________________________

Alan Hardisty

http://www.it-eye.co.uk
http://alanhardisty.wordpress.com
http://www.exchange-certificates.com

(in reply to akersrus)
Post #: 7
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 11:48:06 AM   
akersrus

 

Posts: 18
Joined: 18.Nov.2010
Status: offline
I have done all that you have suggested, Including going to MXtoolbox..
We did have one of our users get a pretty nasty worm about 4 months ago.
We were blacklisted at that time by several companies. all have let go except one. And they still have us blacklisted. Sorbs has been a pain in my behind, there seems to be noway to be de-listed without paying them. and I won't do that. how do you spell extortion? But thianks again for your help. time will tell if the crap email stops.
Tony

(in reply to alanhardisty)
Post #: 8
RE: Non existant email addresses sent to our domain. - 18.Nov.2010 2:05:25 PM   
alanhardisty

 

Posts: 389
Joined: 28.Feb.2010
Status: offline
You should easily be able to get off SORBS if you are configured properly and not sending out spam.

Do they show you are reason on MXTOOLBOX for the listing on SORBS (is there a link to follow to see why)? If there is - please click on the link and advise me why you are listed and if the listing was recent.

_____________________________

Alan Hardisty

http://www.it-eye.co.uk
http://alanhardisty.wordpress.com
http://www.exchange-certificates.com

(in reply to akersrus)
Post #: 9

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