Everything was working fine for months since I set up 2-factor authentication, until all of a sudden the credentials box popped up this morning and I have not been able to send e-mails via Outlook - they sit in the Outbox. I tried logging out of Zoho and logging out of Microsoft, and when I logged back in was not asked for 2FA. This is a business e-mail account and I need it to be working again asap.