Exchange 2010: “You can’t send a message on behalf of this user unless you have permission to do so”

An user had “Send-As” permission on a shared mailbox. But user couldn’t send e-mail as “shared mailbox”.  User is doing it correctly (add the shared mailbox name in From field). But user gets this bounced message:

You can’t send a message on behalf of this user unless you have permission to do so. Please make sure you’re sending on behalf of the correct sender, or request the necessary permission. If the problem continues, please contact your helpdesk.

If user tries OWA to send the e-mail as the shared mailbox, it may work. If it is,  then it’s Outlook issue.

Solution: Have user update the offline address book (click Send/Receive tab, click Send/Receive groups and select Download Address Book). Better yet,

  1. Close Outlook
  2. Delete the offline address book folder under “C:\Users\username\AppData\Local\Microsoft\Outlook\Offline Address Books”  (I assume it’s Windows 7 computer, look under C:\documents and settings\username\…. for XP computers).
  3. Open Outlook and let it download new OAB.

Other Possibilities are,

  • You just gave “Send-As” permission for the user. Then, you have to wait for few hours. (you may restart Information Store to take effect the permission right away, who wants to do it? Smile)
  • User’s Outlook got bad/outdated cached contact information. Search for *.NK* files under user’s profile and delete it. Obviously Close the Outlook first before you delete the *.NK* files.

If it helped you, drop a reply to this blog.


58 comments on “Exchange 2010: “You can’t send a message on behalf of this user unless you have permission to do so”

  1. Jake says:

    worked like a charm. thanks!

  2. […] items folders, as would be expected with the SMTP error. I have found some stuff that might help here and here, although the second link basically tells me it's an issue with a setting on the Exchange […]

  3. dfowler says:

    Getting this error when a user tries to update a recurring meeting. He gets this error for all attendees of the meeting. Any suggestions?

    • You can try this,
      1. Genereate offline address book at the Exchagne server?
      2. Download new offline address book on the user’s Outlook after 10 minues.
      3. Try updating the recurring meeting again.

      You can also have the user try updating the recurring meeting using OWA.

  4. Aten says:

    Life saver thank you very much. Microsoft may have his reasons not to facilitate Send As permissions management in the exchange information store but it is still annoying.

    This solves for me.

  5. anonymous says:

    thanks, your first suggestion worked for me.

  6. Matt says:

    AWESOME ! ! ! ! you’ve saved me about 2-3 hours of troubleshooting ! !

  7. […] Exchange 2010: “You can’t send a message on behalf of this user unless you have permission to do…. Share this:TwitterFacebookLike this:LikeBe the first to like this post. Categories: Office 365 Comments (0) Trackbacks (0) Leave a comment Trackback […]

  8. decooutlet says:

    yes it works thanks

  9. Tan says:

    Yes update OAB works right away .
    thanks so much
    Tan Tran

  10. Mick Dann says:

    This has been driving me round in circles for a week or two now. Hopefully your suggestions will sort it out. Seems wrong to me that all of the permissions are set on the server but the client is able to refer to a locally cached, obsolete “temporary” file and ignore what the server should dictate.
    I was hoping that all of the idiotic “OAB” issues from Exchange 2003 would have been fixed for Exchange 2010, obviously that’s too much to ask. What a shambles !

  11. Dan M says:

    Exchange 2007, Outlook 2010, re creating OAB worked a treat thanks.

  12. Johnyrebs says:

    This just saved me hours of troubleshooting, now I can actually test all the user accounts that I have to create through the day.

  13. Sports Team says:

    Perfect – second option worked for me – user was recently migrated from 2003 to 2010 server.

  14. C. Li says:

    Clearing the OAB’s helped. Thanks!

  15. lee says:

    Second optioned worked for me


  16. Grazer says:

    Yep – I just needed to download OAB in the outlook clicent, didn’t need to delete the OAB files. Thanks for posting.

  17. M Emeric says:

    This issue drove me nuts…kudo’s to you for solution (deleting OAB and downloading new)! BTW, had another issue that drove me crazy also…user could not download latest version of OAB because of…wireless mouse. Here’s a link in case you ever run into this issue: . Cheers!

  18. Everyone loves what you guys tend to be up too. This kind of clever work and reporting!
    Keep up the terrific works guys I’ve included you guys to my blogroll.

  19. Kevin says:

    Hi Anand, I’m having this same issue. Your suggestion to try and ‘send as’ from OWA worked for me, which is great progress. But after I closed Outlook, deleted my OAB files, restarted Outlook I still cannot ‘send as’ from Outlook. What else can I do??

    • You can open Exchange Management Console and generate another offline address book. Then wait for 15 minutes, Open Outlook and try downloading the offline address book.

      I am guessing Server didn’t generate the offline address book with the changes you made (send as permission). So Outlook doesn’t know it’s has the permission.

  20. MrModnick says:

    Рад Встрече!

  21. Samuel says:

    if you just added the send as options I recommend removing then reading the email address from the profile (in control panel>mail) it does it right away and you sound much better talking to your customer then just saying you have to wait a couple hours

  22. Hi there, after reading this awesome paragraph
    i am also delighted to share my familiarity here with colleagues.

  23. DRAGOS says:

    after deleting offline address book works perfect!

  24. Pinto says:

    Thanks Anand. it worked. good on ya

  25. Krd says:

    this helped me a lot, thanks

  26. injunnift says:

    A clean fast is better than a dirty breakfast. Infippins

  27. Navishkar Sadheo says:

    Thank you, it worked for me

  28. Abid says:

    it works. thanks

  29. Christian says:

    Beyond doubt, there’s a great number of beneficial content in here!

  30. Next week, I will need to come up with a document relating to
    this topic, therefore, you ended up saving me considerable
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  33. K says:

    Bullshit tried everything you suggested, dint worked waste of time…. we using outlook2010, our users getting same error massage when sending on-behalf

  34. Johhny D. says:

    Worked great! Thanks for your time to make the article. Tried everything else to no avail.

  35. Gaz says:

    Found this after I had fixed it but dropping a reply because it is the fix!

  36. Theodolus says:

    One other thing you can try. If you have created a new e-mail domain you may have borked the end users ability to send-as. All permissions will be right. All the above solutions fail to fix the problem.

    Create a new mail as the user and remove the e-mail address from the ‘From’ drop down and then re-add it. It’s a fringe case, but that’s what resolved it for me.

  37. Blade says:

    Had spent two days pounding my head against this. I had 3 users suddenly not able to send as, who had been sending as for years. Looking at it from both the server and permissions side and the client side. Today I ruled out the server, but still had no idea why the client wasn’t behaving. I had removed and rebuild the .pst and .ost files, and was nearly ready to wipe their profiles. I went in, saw two offline address books for each of the afflicted users… Deleted them, opened outlook and it worked perfectly. Thanks!

  38. Atila says:

    Deleting OAB worked like charm!

  39. mikainz says:

    Deleting OAB worked for me, too!

  40. Matthew says:

    Just an FYI.
    Had a similar issue when a user was trying to forward a contact card. Tried all the steps but nothing worked. It ended up being a corrupt contact card. Deleted it and recreated and it resolved the issue.

  41. lauraf11 says:

    I have been working on this for hours. Luckily after many searches I stumbled on this solution and it worked! Thank you so much.

  42. rodbk says:

    Brilliant – thanks!
    Tested OK in OWA so followed steps 1, 2 & 3. Saved a call to my helpdesk 🙂

  43. norm says:

    Deleting the offline address book worked for me as well! Office 2016 running on Windows 10 against Exchange 2010 SP3.

  44. warren says:

    bounced the information store. all working 100 % now.

  45. […] Exchange 2010: “You can’t send a message on behalf of … – Exchange 2010: “You can’t send a message on behalf of this user unless you have permission to do so” […]

  46. Frank says:

    Great solution, thanks, was searching for a longer time to a solution and thanks to you I’ve found it!!


  47. John says:

    For me, all above didn’t work but the following worked:
    1) Set Outlook in to online mode (uncheck “use Exchange-cached mode” in the outlook Profile)
    2) Close Outlook
    3) Delete all offline Cache C:\Users\\AppData\Local\Microsoft\Outlook\*.ost
    4) Start Outlook and put it back in Exchange-cached mode)

    This is to be used when the send as via OWA already works but does not want to work via Outlook.
    This has been tested with Outlook 2016 and Exchange 2010 as backend.

  48. Cranky_SysAdmin says:

    This worked a treat! Thanks!

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