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My situation is this:

I had a distribution-group, let's call it

Old Leaders

But, since the member-base had grown and they wanted to be able to send mail (from that adress), I thought "Hey, let's turn it into a Mailbox".

So, I deleted the distrubition-group and added a new mailbox (with the same adress), let's call that

New Leaders

My problem is the following:

Since Outlook caches all the address's it encounter by default, I'm now stuck with a large group of users which, whenever they try to send a mail to New Leaders, their mail end up being reported as "Undelivereable".

Now, to my question:

Is there any way to clear the cache of Outlook for a large amount of users without actually doing it by hand?

(Also, I had somewhat of a brainfreeze when I wrote the subject, so if you think of something more appropriate, please do change it!)

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So is it caching the old distributions email? Also, is the mailbox the exactly same name as the old distribution group? Have you tried sending it via OWA or does it only not work on certain users PC's? – Joe S Jan 16 '12 at 12:28
Sending via OWA works, and the problem only exists on the PC's which haven't had cacheing turned off in Outlook. And yes, the name is exactly the same name as the distrubition-list (which is why the problem is there in the first place; outlook sends with the "/o=*/OU=*(GUID)/CN="-etc (Which is the cached address). When you type, for example "", Outlook sees it as "/o=*/OU=*.." and sends with that address (so as to instruct the sending server that it's an internal address), which is a huge problem since the cached GUID and what-not doesn't lead to New Leaders.) – Marcus Hansson Jan 16 '12 at 13:59
Ah ok, and do you want to clear all the cache or just remove that email address? As you could create a batch file to remove the NK2 file and add that to the logon script or logoff script. – Joe S Jan 16 '12 at 14:36
Mmmh, that's actually a viable solution. Do you think there's a command (line or GUI, doesn't matter) to force exchange to recognize mail directed toward Old Leaders as mail meant for New Leaders? Would be awesome since this mailbox is "publicly" visible. – Marcus Hansson Jan 16 '12 at 15:05
If you ran a script to remove the NK2 files, you wouldn't need a script do redirect as you said they are the exact name. You just changed it to be a mailbox. So it was say (distribution group) and its still as a mailbox, right? Do you want a batch file to remove the NK2 file? – Joe S Jan 16 '12 at 15:14
up vote 1 down vote accepted

The email addresses are saved in an NK2 file which means you can use a batch file to remove the NK2 file. This can be added to either the logon script or logoff script (personally I'd add it to the logon script). This will then delete the NK2 file and no emails will be cached on that PC anymore.

Here is a little batch file I mocked up (just in case you or anyone needed it):

SET NK2LOCN="%APPDATA%\Microsoft\Outlook"

Let me know if there is anything else related to this topic that I can help you with.

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