Basic Authentication and Exchange Online – June 2021 Update

Greg Taylor - EXCHANGE- IMAP was disabled on our tenant even though we were using it in conjunction with a 365 App Password for one of our (internally developed) applications to retrieve emails/attachments from my mailbox.  I don't personally have access to our 365 Admin for this tenant, but worked with one of our IT admins through the steps above and, used the Help Article tool to re-enable IMAP, but it's still not working.  My app is getting "xm001 NO LOGIN" when it attempts to establish the IMAP connection.

How long does it take for the Help Article tool to take effect after you've re-enabled IMAP?
(If it matters, our tenant is, maybe, a few 100 users.)

After October, what path/protocol/method are we supposed to use to facilitate this type of work flow?

Is there an 365 Exchange API, another protocol we can use in C#/.NET or something?  I haven't been able to find a clear answer on this yet.

Couple other things:

• while I don't have 365 admin to this tenant, I am a MS Partner and have a fairly good understanding of 365 admin in general
• things were working fine for 2+yrs prior to about 2:30AM EST today
• my account has MFA enabled and using a 365 App Password to make the IMAP connection (we cycled the MFA and App Password today just to make sure something wasn't stuck there).
• it's been about 35mins since we re-enabled IMAP in the Help Article tool

THANKS! 🙂

-------------UPDATES----------:

• It took about 42mins for our tenant, but programmatic IMAP access w/ a 365 App Password seems to be working again for us. 
• When possible, I'd still like any info you can provide that informs us what protocol/methodology we should be implementing now for when this IMAP access ultimately gets taken away in October.  Thanks again!