This is what you need to do.

Press Alt-e and choose 'Account Settings' from the drop-down menu that appears, then click 'Server Settings' under the account and enter these details:—

 Server Name: outlook.office365.com
 Port: 993
 User Name: <your e-mail address>
 Connection security:  SSL/TLS
 Authentication method: OAuth2

Now click 'Outgoing Server (SMTP)' in the left hand column. Double click the 'Outlook.com (Microsoft)' entry and enter these details:—

 Server Name: smtp.office365.com
 Port: 587
 Connection security: STARTTLS
 Authentication method:  OAuth2
 User Name: <your e-mail address>

Dear Sir: I'm all following your advice, but the drop down box DOESN'T HAVE OAuth2 to choose from ! It had it for the IMAP settings but NOT FOR THE SMPT settings Is this a MS problem? What should I do ? I am a fan of TBird since it probably began..and would like to continue using it for my email.

Just in case, I down loaded MS Outlook for email. At least I can figure out how to use their program so I don't miss paying bills that have been discontinued as paper billing. mj

You need to change the server name and restart Thunderbird for the oauth to become available.

Note especially the server name for SMTP: smtp.office365.com

I wrote a long drwarn out reply before realizing it is not going to POST! Thanks to Matt(whom informed me to "restart" so I locate the OAuth2 from drop down box) and ThePillenwefer (who gave me exact details for the IMAP & SMPT). However, when I do this TBIRD sends or receive NO emails . QUESTION: When can make changes.....Sept 16th or before?.....Basic Authentication no longer available to access any Outlook account////////////////// IF I can make changes before this date, why does a window appear over TBird email which informs me that cookies are needed to sign in? Window says: " We can't sign in. Your Browser is set to block cookies, You need to allow cookies , check the online help in your web Browser" (I have ADBlock) My default browser is FoxFire. Please help

The browser in this instance is Thunderbird and you must have cookies enabled in Thunderbird.

Perhaps try working through the support documentation in this. https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202#w_your-outlook-or-hotmail-password-no-longer-works-with-thunderbird-and-you-cannot-send-or-receive-email