Outlook 2010 Refuses to Deliver E-Mail stating “the e-mail address is no longer valid”
I have front-ended my Exchange Server 2010 with sendmail, preferring to use Linux utilities such as SpamAssassin and Clam AV to filter out the bad stuff before sending it to my email server. I also create generic email addresses that I use to give out. Recently, I was having a difficult time sending an email to a newly created email address with a domain that is served by my Exchange Server. In Outlook 2010, after inputting an email address such as special-email@epicminds.com, Outlook would display “this e-mail message cannot be delivered to special-email@epicminds.com because the e-mail address is no longer valid”.
The resolution for this issue cannot be found in Google – no hits are found for the exact error message. It occurred to me that since the Exchange server was responsible for the domain, it was determining the email address was invalid, and this is indeed the case. The solution is simple: change the Type for the Accepted Domain in the Hub Transport from Authoritative to Internal Relay.
To recap:
- Start Exchange Management Console
- In the console tree under the Exchange Server select Hub Transport under Organization Configuration
- Select the Accepted Domains tab
- Right-click on the accepted domain and select Properties
- Change the Type to Internal Relay Domain
- Click Apply
This will enable the Outlook client to accept an email address using that accepted domain that does not have a mailbox tied to the address.










August 10th, 2010 at 1:39 pm
On Outlook 2010, Exchange 2010 on 2008 r2 Windows Server: I have this exact error, but it’s on one of our own user addresses (internal). Other users in our organization can send email to a specific internal user address just fine, however, one of our internal users is getting this error message when she tries to send to the same user IE: mark.smith@yourdomain.com (all other users can send just fine, one user gets “this e-mail message cannot be delivered to mark.smith@yourdomain.com because the e-mail address is no longer valid”. ) Nothing special or different about the user email address and it looks fine on Exchange.
Typed in name and click on “Check Name” and it comes back as a good name (underlined). When I chose the address manually from the address book and select to send mail, it brings up the new mail screen with the user just fine for a few seconds then sets it back to “this e-mail message cannot be delivered to Mark.Smith@yourdomain.com because the e-mail address is no longer valid”.
Tried downloading a updated address book to this affected user, but nothing changed with this address and her ability to send to it.
September 8th, 2010 at 9:41 am
Debra,
Any chance, did you get this resolved?
Thanks,
Iamme
September 9th, 2010 at 8:28 am
I have found that if you run in Safe Mode this does not occur. That points to an Add-in issue. Perhaps the new “Business Connectivity” services that link to Sharepoint? I am going to checkout communication with our Sharepoint servers.
September 13th, 2010 at 9:41 am
I’ve found that such thing as Dabra describes can be because user has same contact in Personal Address Book as in OAB. Syncing of those contacts do the job for us.
February 2nd, 2011 at 2:13 pm
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.
March 23rd, 2011 at 2:52 pm
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.
April 29th, 2011 at 10:10 am
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.
June 1st, 2011 at 5:32 am
using daughter’s email adderss
July 20th, 2011 at 2:14 pm
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.
July 20th, 2011 at 6:58 pm
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.
December 7th, 2011 at 8:20 pm
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
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.
December 8th, 2011 at 10:10 am
Yes, clearing the user autocomplete also fixed this problem for me.
Thanks,
Wim
January 6th, 2012 at 11:59 am
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.
January 11th, 2012 at 2:50 pm
I was able to solve this for a user following the “disable cache mode” and then re-enabling it. Problem disappeared.
April 10th, 2012 at 11:08 am
“I was able to solve this for a user following the “disable cache mode” and then re-enabling it. Problem disappeared.”
Same here. Just clearing the cache didn’t fix it. I had to disable thenr reenable.
Thx DC>
January 7th, 2013 at 4:47 pm
Same for me as well. Manually deleting the one nickname entry didnt do it, and the user was very upset with having the clean all the auto completes out of there.
So I am happy that simply unchecking cached mode. closing outlook, restart outlook, re-enable cached mode, close outlook, restart outlook, fixed it completely!