My search foo is lacking today. I'm sure this question has been asked and answered but I could not find it. In Thunderbird (V. 102.13.1; 64-bit; Windows 10 Home) I'm getting this error pretty consistently when trying to send email. (see attached) It is happening with several email accounts. When I look at SMTP settings all appear to be OK. I have tried supplying the password again - copied and pasted - and the failure continues. If it matters, I use several different email services including my ISP (which is where this error is today), gmail, and fastmail. As far as I can determine port settings and connection verification settings are correct and are set up for each service's SMTP servers to receive mail from me. Can someone please point me to an easy-to-follow guide on how to fix this?