I should note that I have attempted multiple other approaches including other authentication methods and security protocols The settings above are the only ones that reached the usual, first-time authentication browser dialog that Outlook users see. eventually throwing an error that the user/password combination is invalid. All appears exactly as it should but, as the send is further processed, it hangs. This guide is specifically for current Purdue users of Thunderbird who are migrating.

If you don't see yours listed here, ask your email provider to give them to you. Here's a list of those settings for several email providers. Subsequently, upon entering the correct password, it sends me a text with the six-digit code, which I enter. You'll need your email provider's incoming server settings (POP or IMAP) and outgoing server settings (SMTP). When the smtp connection is made for the first time, Thunderbird's internal browser opens and asks for the account password. The SMTP settings are (as specified by Microsoft): For Microsoft 365, the server name for IMAP and POP is and the server name for SMTP is.

As per my knowledge, that certificate prompt should be the cause since during the email transmission, certificate is need to verify sender's domain is safe or not. I currently have to use the browser to send email because I cannot get the Thunderbird outgoing server to authenticate properly. From your description, you SMTP configuration for Office 365 in the Thunderbird is correct. Our company recently changed our email server to a multi-user, Office365 account. Please note that Thunderbird version 78.0 is only offered as direct download.

Thunderbird office 365 smtp