Forum Discussion
SMTP XOAUTH suddenly failing for Outlook personal with '535 5.7.3 Authentication unsuccessful'
Hi please this is a helpful discussion below, but MTC is not technical support, so you need to contact Microsoft support directly.
https://answers.microsoft.com/en-us/msoffice/forum/all/535-573-authentication-unsuccessful/cd915151-ae89-4505-8ad3-29680554e710
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.
