All of a sudden, I'm getting a "SMTP server doesn't support STARTTLS" error when trying to send an email

That could be a transitory issue with the server, give it a bit of time and see if it goes away.  Also, go to your provider’s website to see if they changed their security settings.

Thanks Jay.  It took a few hours, but all of a sudden, the emails went through.  Some what strange.

It was no doubt a server issue.  When things change, but you haven’t changed anything, look to the server.

Jay, I’m not to good with the computer as you probably figured yesterday. But everything with the eM Client has been great–until the last week or so.  Like yesterday and this morning, I would try to send emails and I would get the SMTP/STARTTLS error.  As you said yesterday, they finally came through.  But now, along with the errors, I’m starting to send emails and they are going nowhere and not showing up.  Just wondering how to deal with this if you have the time.  Thanks

Occasionally, things will get stuck in the outbox due to invalid addresses, etc. and it can block newer, valid sent items from going out. The outbox is a local folder that should show in the smart folders section.  If it does not, right-click on any smart folder, click on display and make sure “Outbox” is checked.  Then open the outbox and delete anything in it.  Now, try to send an email to see if it goes through.  If not, it is no doubt a server issue that you should take up with your provider.

Outbox is fine.  Any suggestion regarding a good server?  I’ve got an old one.

When I mentioned server, I was referring to the provider’s server, not yours.  Sorry for the confusion.  I would contact your provider and see if they are experiencing issues.

See if this post might help.