Forum Discussion
SMTP XOAUTH suddenly failing for Outlook personal with '535 5.7.3 Authentication unsuccessful'
Deleted Thanks, but that's about Office 365 accounts with SMTP AUTH disabled, but this issue is about personal accounts (Outlook/Hotmail/Live).
So, it is not the same issue.
Moreover, this problem does not occur for Office 365 accounts in the same setting.
"535 5.7.3 Authentication unsuccessful for smtp.office365.com for personal accounts"
This is a common error and sometimes it is worth reading the shared thread in its entirety
Best regards
Deleted I did my research before posting here. Believe me, those articles won't help to solve this problem. Quite some people using multiple apps are suffering from this, and all of a sudden. Therefore, this is likely a problem at the side of Microsoft, again, unfortunately.
" Therefore, this is likely a problem at the side of Microsoft, again, unfortunately"
I understand, but it is complicated and rather this post - will be another submission.
https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission
Please this is official documentation.
So, what do you propose to do? Contact Microsoft? If so, how? There doesn't seem to be a https://support.microsoft.com/contactus for Outlook/Hotmail/Live, so ...