Office365 SMTP 535 5.7.3 Authentication unsuccessful


Expected behavior:

Sending E-Mail trough Office 365 SMTP Account

Actual behavior:

Sometimes (maybe 1% of all answers) I get:
Can’t use Channel::Driver::Smtp: #<Net::SMTPAuthenticationError: 535 5.7.3 Authentication unsuccessful

Steps to reproduce the behavior:

Configure office365 as sending smtp

Is there any existing knowing bug?, some of our answers will not be sent from Office365 SMTP, because auf unsuccessfull Authentication. Then we have to reenter our credentials at E-Mail Accounts Settings Page, and all is fine again for some days.


I’m not aware of this problem, we have several hosted instances with office365 without those problems.

I think it’s hard to narrow that down if you can’t reproduce that steadily. It might some security thingie with Microsoft. Who knows.

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