Receiving mail for users that are no longer in the Information Store

[sierrapacific]

I have exchange 5.5 w/SP4 and have removed employees that are no longer with the company. Their mailboxes have been deleted as well as the user accounts. However, our domain still receives mail for them. How can this be? Doesn't the exchange server reject mail if the mailbox does not exist on the information store anymore? I made sure they weren't hidden mailboxes either. Any ideas?

 

[zbnet]

Your server will accept mail for any address whatsoever at @yourdomain.com - only after it has received it can the server then try and resolve the recipient SMTP address(es) against the GAL. What it does when this resolve fails depends on your setup - by default, Exchange generates an NDR that it returns to the sender, although some time ago MS released a patch that enables you to prevent the generation of these NDRs (although the patch seems to be no longer available since 5.5 went out of support).

Just because you remove a mailbox and the associated SMTP address from your server doesn't stop other people sending these addresses email. There is every chance that you will continue to receive email for these addresses for years to come, especially if the addresses have found their way on to spammer lists.

One simple workaround if you just want Exchange to silently disgard these messages is to create an empty DL, and assign these old SMTP addresses to this DL as secondary proxy addresses. That way the inbound messages get delivered to the empty DL, which swallows them into a black hole.

 

[Griffyn]

For those who have the patch, I'd advise staying away from it, or re-enabling NDR generation if you are using it (

http://support.microsoft.com/?id=837794).

I've found that mail is sometimes not delivered with it enabled.

For example, Remote person e-mails my company with two e-mail addresses in the To field. One of the e-mail addresses is valid for a mailbox, the other is not. No NDR will be sent to the sender (because they've been turned off), but the message will not be delivered to the valid recipient either!

 

[dennisbbb]

That is not true at all regarding the patch.

You may have set your spam filter to delete such email before reaching the Exchange server.

 

[Griffyn]

Hi dennisbbb,

We don't have a spam filter, or any other such mechanism to intercept mail.

I have just tested the setting I mentioned above and can confirm exactly what I said. I sent two e-mails to the same domain. The first had an invalid user for the recipient, the second had a valid user and an invalid user. The sender received an NDR for each, and the valid user received the second e-mail.

With the NDR's suppressed, no NDRs are sent to the sender, and the valid user does not receive a copy of the e-mail.

 

[zbnet]

Griffyn, what number do you have in the SuppressNDROptions value? Have you tried the other values to test the behaviour?

What SP and hotfix level are you at?

 

[Griffyn]

I had the SuppressNDROptions value set at 10 (hex). I haven't tried any other values except for 0 (disabled).

I have SP4 applied, not sure how to measure what hotfix level I'm at - the build number in the Exchange Administrator is 2653.23

I also tried the SuppressNDROptions value at 1, but it still doesn't deliver to the valid recipient.

 

[zbnet]

The build number of the Admin isn't a good indicator of what patch level you have installed, the admin.exe rarely gets patched in a hotfix.

Check whether you have the post-SP4 rollup hotfix installed (

http://support.microsoft.com/?kbid=841765).

If not, I would recommend it, this is the closest thing to SP5 for Exchange 5.5, it cures a number of fairly significant store-based issues.

I've not heard of the NDR patch being dependent on this, but you never know.

 

[Griffyn]

I didn't have the post-SP4 update installed - I have now installed it. I'll re-test the NDR issue when I get a moment.