Bugzilla

copy from bug 1799259 comment 8 (my post)

> Environment: Win 10 22H2 x64, M365 personal account 
> IMAP: outlook.office365.com, TLS/SSL (993), OAuth2
> SMTP: smtp.office365.com, STARTTLS (587), OAuth2
> 
>     Tb 102.7.1 x64 + brand new profile
>     Tb 110.0b3 x64 + brand new profile
>     Tb 111.0a1 (20230201095127) x64 + brand new profile
> 
> In all cases, IMAP is good. The scope used for OAuth2 is outlook.office.com, not outlook.office365.com.
> On the other hand, SMTP is bad. As same as bug 1775077, login failed dialog appears, but neither "Retry" nor "Enter New Password" works, endless loop...


(In reply to Andrei Hajdukewycz [:sancus] from comment #10)
> Microsoft disabled SMTP auth by default some time ago. Please make sure it's actually enabled at https://admin.exchange.microsoft.com/#/settings by unchecking [the box shown in this screenshot](https://i.imgur.com/xPf9wG1.png) at Settings -> Mail Flow.
> 
> Note: It may take a few minutes for the SMTP server to reflect the change. It did for me.

It is not applicable for M365 personal account.

> If you have this box unchecked already, and still can't send, an error from the error console in Tools -> Developer Tools -> Error Console would be very helpful.

Error console log 102.7.1 :

(login fail dialog)

mailnews.smtp: Command failed: 535 Authentication unsuccessful [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:03:56.225Z 08DB048C484F1486]; currentAction=_actionAUTH_XOAUTH2 SmtpClient.jsm:515:19
mailnews.smtp: Error during AUTH XOAUTH2, sending empty response SmtpClient.jsm:1038:19

(click "Retry")

mailnews.smtp: Command failed: 500 Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:01.287Z 08DB048C484F1486]; currentAction=_actionAUTHComplete SmtpClient.jsm:515:19
mailnews.smtp: Authentication failed: Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:01.287Z 08DB048C484F1486] SmtpClient.jsm:701:17
mailnews.smtp: Command failed: 535 Authentication unsuccessful [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:23.004Z 08DB048C484F1486]; currentAction=_actionAUTH_XOAUTH2 SmtpClient.jsm:515:19
mailnews.smtp: Error during AUTH XOAUTH2, sending empty response SmtpClient.jsm:1038:19

(click "Enter New Password")

mailnews.smtp: Command failed: 500 Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:28.050Z 08DB048C484F1486]; currentAction=_actionAUTHComplete SmtpClient.jsm:515:19
mailnews.smtp: Authentication failed: Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:28.050Z 08DB048C484F1486] SmtpClient.jsm:701:17
mailnews.smtp: Command failed: 535 Authentication unsuccessful [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:43.533Z 08DB048C484F1486]; currentAction=_actionAUTH_XOAUTH2 SmtpClient.jsm:515:19
mailnews.smtp: Error during AUTH XOAUTH2, sending empty response SmtpClient.jsm:1038:19

(click "Cancel")

mailnews.smtp: Command failed: 500 Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:48.564Z 08DB048C484F1486]; currentAction=_actionAUTHComplete SmtpClient.jsm:515:19
mailnews.smtp: Authentication failed: Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:48.564Z 08DB048C484F1486] SmtpClient.jsm:701:17
mailnews.smtp: Authentication failed: Unrecognized command 'unknown' [TY2PR02CA0002.apcprd02.prod.outlook.com 2023-02-02T03:04:48.564Z 08DB048C484F1486] SmtpClient.jsm:742:19
mailnews.send: Sending failed; Unable to authenticate to Outgoing server (SMTP) smtp.office365.com. Please check the password and verify the 'Authentication method' in 'Account Settings | Outgoing server (SMTP)'., exitCode=2153066805, originalMsgURI= MessageSend.jsm:335:27