Outlook "new" does not sent emails with one of ma 3rd-party accounts

Question

MessageDeliveryFailedException: Could not deliver the message [len=70, data=00000000BDA695358C98D34F97C2CBBD531706D60700F727D610CB36F94DAB1EF4023B5D592100000000010F0000F727D610CB36F94DAB1EF4023B5D59210001E63602EC0000].

Failure code: c355

the affected adress ist from kablebw / vodafone.

I need solution - was working for nearly 2 years without problems since 3 month it is not working to send mails out of the outlook mailbox.

I do not want use outlook classic - there it is working in parallel witout problems

B.r. Bernd

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Moved from: Outlook | Windows | New Outlook for Windows | For business

Answer 1

Hi Bernd, I get how annoying it is when something that’s been working for years suddenly stops. The problem isn’t with your Vodafone account, it’s because New Outlook now uses a different sync engine than Classic Outlook, and recent updates have caused issues with sending mail through IMAP/SMTP accounts. The easiest fix is to remove the account and add it back manually, making sure the outgoing server is set to smtp.vodafone.de with SSL on port 465 or TLS on port 587, and that authentication uses your full email and password. Also check that New Outlook is fully updated since Microsoft has been rolling out fixes for this. If that doesn’t help, creating a fresh Outlook profile can clear any cached errors. Quick question, are incoming emails still working fine, and does the error pop up right after you hit send or only after a delay?Regards,
Aron

Answer 2

this is not a 3rd party problem - because with outlook classic all 3rd-party IMAP mailboxes are working properly!

The failur occurs only with outtlook new since a couple of weeks - deinstallations an repair functions are not successful

Answer 3

Same failure with all workarounds tested