Comments on: Outlook 2010 Refuses to Deliver E-Mail stating “the e-mail address is no longer valid”

By: DC

DC — Wed, 11 Jan 2012 19:50:53 +0000

I was able to solve this for a user following the “disable cache mode” and then re-enabling it. Problem disappeared.

By: kashif shahzada

kashif shahzada — Fri, 06 Jan 2012 16:59:56 +0000

This method fixed it for me…try this

Method 2

Outlook 2010
Use one of the following methods to reset the whole Outlook nickname cache for Microsoft Outlook 2010.
Method 1
1.With Outlook 2010 open, click File (BackStage), and then click Options.
2.Click the Mail tab.
3.Under Send Messages, click Empty Auto-Complete List.
Outlook will generate a new nickname cache.

By: wdh2880

wdh2880 — Thu, 08 Dec 2011 15:10:51 +0000

Yes, clearing the user autocomplete also fixed this problem for me.

Thanks,

Wim

By: Lendl

Lendl — Thu, 08 Dec 2011 01:20:19 +0000

I was having the same problem the below blog solved my issues maybe it solves yours to

http://forums.msexchange.org/m_1800542177/mpage_1/key_/tm.htm#1800542177

Perform the below steps

How to remove nickname cache entries, one at a time
Outlook 2010
1.Open a new email message.
2.Type the first few characters of the nickname cache entry that you want to remove from the cache.
3.When the entry appears in the “suggested names” list, move your mouse pointer over the name until it becomes highlighted. (But do not click the name).
4.When the “X” icon appears next to the highlighted name, click X to remove the name from the list.

Method 2

By: Joe Hamrick

Joe Hamrick — Wed, 20 Jul 2011 22:58:39 +0000

I’ve seen this issue here and there as well. All the users it’s happened to were using outlook in chached mode. Turning off chached mode and restarting outlook worked for me. The next time it comes up though I think I’ll give Shellipe’s method a try.

By: Shellipe

Shellipe — Wed, 20 Jul 2011 18:14:24 +0000

I had a user with only a few entries with this problem. Instead of deleting the whole auto complete cache, I just deleted the users in the auto complete list by clicking on the x. In the new email box, type the recipeint’s name. When it appears in the auto complete list, click on the x next to the name to delete it. Restart Outlook and re enter the recipeints name using check names on the ribbon. Should work. If this problem is for all recipients, go to File/Options/Mail/Send Mail/User Auto complete and to the far right click on Empty auto complete list. That will empty the cache and you will have to rebuild using the check names in a new email.

By: Sherron Glenn

Sherron Glenn — Wed, 01 Jun 2011 09:32:59 +0000

using daughter’s email adderss

By: Chad Pearson

Chad Pearson — Fri, 29 Apr 2011 14:10:08 +0000

For internal users, you can also delete the contact, find them in the GAL, right-click, Add to Contacts. This leads me to believe its another OAB or OST issue.

By: Bobby Powell

Bobby Powell — Wed, 23 Mar 2011 19:52:45 +0000

I had the same error message showing up on clients here and there. Ran: Update-GlobalAddressList -Identity “Default Global Address List”
Downloaded the address book to the client again, problem solved.

By: Lisa Olinda

Lisa Olinda — Wed, 02 Feb 2011 19:13:58 +0000

I had a similar issue and resolved by changing type to “External Relay”. I then had to clear the auto-complete cache. Thank you for pointing me in the right direction.