Office365 SMTP authentication issue

[dblach]

Hi,

I have recently lost the ability to send emails using my university O365 account through the proxy.
My config was working perfectly well until today, now only IMAP remains operational.
When attempting to send an email, my client (Outlook 2010) shows the password input prompt despite the password is being stored in the settings. Entering a correct password results in the same window appearing in an endless loop.

I have installed the latest release, recreated the config based on the sample and, finally, reauthenticated the account, but this did not help.

Log file shows the following:
2025-03-02 18:55:42,502: Accepting new connection from 127.0.0.1:58175 to SMTP server at 127.0.0.1:1587 (unsecured) proxying smtp-mail.outlook.com:587 (STARTTLS) 2025-03-02 18:55:53,208: Accepting new connection from 127.0.0.1:58185 to SMTP server at 127.0.0.1:1587 (unsecured) proxying smtp-mail.outlook.com:587 (STARTTLS) 2025-03-02 18:56:03,532: Accepting new connection from 127.0.0.1:58195 to SMTP server at 127.0.0.1:1587 (unsecured) proxying smtp-mail.outlook.com:587 (STARTTLS) 2025-03-02 18:56:13,327: Accepting new connection from 127.0.0.1:58206 to SMTP server at 127.0.0.1:1587 (unsecured) proxying smtp-mail.outlook.com:587 (STARTTLS) 2025-03-02 18:56:31,377: Accepting new connection from 127.0.0.1:58217 to SMTP server at 127.0.0.1:1587 (unsecured) proxying smtp-mail.outlook.com:587 (STARTTLS) 2025-03-02 18:58:26,302: Accepting new connection from 127.0.0.1:58229 to IMAP server at 127.0.0.1:1993 (unsecured) proxying outlook.office365.com:993 (SSL/TLS)

After cancelling, Send/Receive task ends with the error code: 0x800CCC92. I know it points to wrong credentials, but these were not changed and the issue affects only SMTP.

Are there any changes related to Office 365?

[dmitriy1980]

Hi, I'm not saying it's related but about 24 hours ago Microsoft had an issue where people were not able to login. I found the same issue wjtg my account where it would take my proper credentials, login, succeed only to ask for credentials when you asked for sync. The issue for my account was addressed but this being less than 24 hours might be still in the wild especially that you said that it started for you only today. Maybe wait for a day or 2 and see if it's fixed by itself. Just my 2 cents.

[dblach]

Hi Dmitry, didn't know about this MS issue you mentioned. This is also the reason why I created this issue here, to see whether it also affects other people. I will keep monitoring and close the thread if it gets fixed.

[dmitriy1980]

No problem. Hope that was it. For transparency, here's the link about yesterday's issue: https://thehill.com/homenews/ap/ap-business/ap-thousands-report-outage-affecting-microsoft-services-like-outlook/

[simonrob]

This wasn't something I experienced myself, but either way I doubt this is something caused by the proxy. I'll leave this open for a while just in case, but feel free to close beforehand if you don't encounter it again.