Create Catch-all account for Exchange 2007

Posted on 2009-07-09
Medium Priority
Last Modified: 2012-06-27
I am trying to create a catchall account for Exchange 2007. I read where I had to disable Recipient Filtering on the EDGE server and create a Transport Rule. By doing this I was catching all emails coming in for the company.

All I want to do is catch emails sent to my domain BUT the mailbox name does not exist. (e.g. Bob Smith's email is bsmith@mydomain.com will go right to his inbox but if a message is sent to bobsmith@mydomain.com then have it sent to the catcall account)
Question by:GMSMRM
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Accepted Solution

tigermatt earned 1600 total points
ID: 24818216

A catch-all account will cause you nothing but problems. It has an administrative overhead to check that mailbox - any email sent to a wrong address will still be accepted, so someone must check that email and process it accordingly.
A catch-all account will also act as a massive spam and virus trap. It is common for abandoners to try simple addresses - e.g. bob@yourdomain.com. All the addresses on their list will be accepted by the server and delivered to the catch-all.

A better solution would be to leave all the standard anti-spam features enabled. This means any email to users who do not exist on the network will automatically be rejected, and an NDR sent to the sender by their mail server. The sender will then know IMMEDIATELY that their message failed, and will take corrective action to ensure it reaches the intended recipient the second time.

Having taken that on board, if you still need a catch-all mailbox, the procedure is at http://social.technet.microsoft.com/Forums/en-US/exchangesvrgeneral/thread/c8fba4d7-4ddb-40ec-b77e-d198da86173f. If you don't have an Edge server, Recipient Filtering is disabled on the Hub Transport server instead.


Expert Comment

ID: 24818350
Are you sure you are configuring the Transport rule for catch-all on Edge server, because it wont work on HUB as it does categorization.

You can follow the link
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Expert Comment

by:Alan Hardisty
ID: 24818358
I could not agree more with tigermatt's comments.
Purely on a statistical basis - 97% of all emails are spam (http://news.bbc.co.uk/1/hi/technology/7988579.stm)
So for every 100 good messages your company gets a day, with a catch-all account, you are going to get on average 3,333 spam messages per day.
Over the course of a year, that equates to 1,216,666 messages that are spam.
Do you really want to look through all that for the ocassional message that might be worth reading?
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LVL 58

Expert Comment

ID: 24818383

To echo Alan's point, consider the disk I/O load that will place the server under. Those emails have to be committed to transaction logs and then to the databases. If you get a sudden burst of spam, you could bring the server to its knees as transaction logs fill the disk.

Email should always be rejected AS SOON as you can tell something is wrong with it. With recipient filtering enabled, this means it is rejected as soon as the sending server mentions a recipient with the wrong email address. The actual email is never exchanged, so the only real load on the server for the spam email dropped this way is a little network activity.

LVL 76

Expert Comment

by:Alan Hardisty
ID: 24818413
Good point - well made.

Author Comment

ID: 24841398
I followed the procedure for creating the catch-all account as suggested, but not suggested, and it works great. However I do consistenatly get emails for employees who are no longer with the company. I added a transport rule to try and drop them but it does not seem to work. Is the catch-all settings overriding this rule?
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Assisted Solution

by:Alan Hardisty
Alan Hardisty earned 400 total points
ID: 24841430
A catch-all is simply that - a catch-ALL.
You will receive ALL mail destined to your server no matter what.  Nothing you can do about the old users.

Author Closing Comment

ID: 31601821
Thank you for your fast and clear answers.

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