Not able to send email from desktop Outlook - failure code ad29

Lenka Milaberská 0 Reputation points
2026-09-03T18:13:36.3166667+00:00

Hello there, I have an issue with sending emails from desktop Outlook app as shown below (failure code ad29). I already tried solution recommended here https://learn.microsoft.com/en-us/answers/questions/5986707/how-to-fix-the-problem?page=1&orderby=Helpful&comment=answer-12932633&translated=false#newest-answer-comment but is not helping in my case. I even tried to delete my mail account from otlook and add it again, no difference. Sending mail from webmail works, from outlook on mobile as well. What should I do next? Thank you

MessageDeliveryFailedException: Could not deliver the message [len=70, 
Failure code: ad29
Outlook | Web | Outlook.com | Email
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  1. Lenka Milaberská 0 Reputation points
    2026-09-09T08:38:05.4566667+00:00

    Hello @Emma1-N and @Hornblower409

    The last tip with deleting all accounts and nuking it has finally helped.

    Thank you for assistance!

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  2. Hornblower409 14,600 Reputation points
    2026-09-06T22:11:59.5+00:00

    @Lenka Milaberská said

    Sending mail from webmail works, from outlook on mobile as well

    Can you please confirm that the problem account is Microsoft Hosted? (e.g. outlook.com, hotmail.com, etc)

    I even tried to delete my mail account from otlook and add it again, no difference.

    One other thing to try is to completely erase your New Outlook for Windows Profile.

    Some cached data remains even after removing an email account and uninstalling the app. You will not lose any data, but you will have to add back all of your email accounts from scratch. It will be like you have never used New Outlook before.

    Remove the accounts, Nuke your New Outlook profile, and re-add the accounts from scratch.

    • View -> View settings -> Accounts > Your accounts
    • Pick an Account and [Manage]
    • [Remove]
    • (o) Remove from all devices (If you see it)

    Then to Nuke the profile see the answer by "Hornblower409 Dec 11, 2025" in
    https://learn.microsoft.com/en-us/answers/questions/5655980/outlook-starting-error-repair-reinstall-reset-does

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