Thunderbird | Intelogist

MGR: the Intelogist 3rd October 2024 No comments

How to: Troubleshoot the error message “Client not authenticated to send mail” (or else, how to configure Thunderbird or other client to use POP/SMTP with a M365 work/school email account)

When you try to send email from a desktop client through your M365 email account, you may be hit with the error message “Client not Authenticated to Send Mail”. Here’s how to solve this.