You have posted this before. The screenshot indicates you have many accounts, possibly 12 if I counted right. Please explain that and I may be able to assist.

I forgot to mention that my current version of Thunderbird is 115.9.0. My email problems started with Thunderbird 115, whose TLS issues were not shared with earlier versions of Thunderbird.

I have an IMAP account that I use presently and a POP account (both created in Thunderbird) that I am not using because it doesn't work well with Microsoft's revised Outlook (which I use to manage my other two email accounts, Gmail (which is synced with my Galaxy S23+ smartphone) and Hotmail(which is tied to my Microsoft 365 account).

I want to delete all other email and outgoing SMPT server profiles and regain the ability to send emails from Thunderbird without having them blocked.

Update: I deleted the redundant SMPT entries per the screenshot image of my outgoing SMPT settings attached below. I've also attached an updated screenshot of my current incoming server settings. Let me know if you need any additional information.

It may help if you post the complete error message you are receiving. Thanks.

I'm getting no error message that I can post you. My attempted outgoing emails wind up remaining in my drafts folder with crossed-out headers.

I'm sending you these screenshots of my drafts folder FYI. You'll notice that time stamps are shown even though the emails failed to be successfully transmitted. I'm also sending you a shot of the TLS error message that I got April 3rd when Thunderbird temporarily blocked my email downloads. I still get this error message even when my incoming emails are finally downloaded (often after I have clicked on the Get Messages cloud icon several times).

Hopefully, you can help me figure out what's going on.

I am not the certificate expert, although there are a few on the forum. I suggest you try STARTTLS with port # 143 and see if that gets you by the error message.

I would also try port 587 on the SMTP server with both SSL/TLS and STARTTLS to cover the bases. I did notice a website that suggested the port change. PLEASE ignore prior post, as port 143 is for incoming. Somehow, I had forgotten the issue is for outgoing.

I've tried everything that you've suggested without success.

Would it help to snooze my antivirus software (Malwarebytes) and dial down Windows Defender firewall?

I doubt it. I also use malwarebytes and windows defender and they seem able to coexist anywhere. You might try doing the opposite on settings, switching to none and port 25 and see if that works. There is a problem somewhere on the connection, but beyond me.

Thanks, David. It appears that your recommended settings for outgoing SMPT server has already unlocked several outgoing emails that were "trapped" in the Drafts folder.

Good, but long-term, that is a security exposure, so I hope you get a cleaner solution soon from email provider.