> the authentication error message that TB presents is giving an address similar to my employer's domain name ... essentially exchange.employer.com.
That is normal, because the auth error is probably generated in IMAP code, which doesn't know about the OAuth2 host. The OAuth2 code is another module, and the "outlook.office365.com" host is hardcoded in the OAuth2 code (in fact, that's what this bug added).
This message also makes sense to the end user, because he wanted to connect to exchange.employer.com, not Office365. You know about OAuth2, but normal users don't.
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> the authentication error message that TB presents is giving an address similar to my employer's domain name ... essentially exchange.employer.com.
That is normal, because the auth error is probably generated in IMAP code, which doesn't know about the OAuth2 host. The "outlook.office365.com" host is hardcoded in the OAuth2 module code (in fact, that's what this bug added).
This message also makes sense to the end user, because he wanted to connect to exchange.employer.com, not Office365. You know about OAuth2, but normal users don't.