TB Returning STARTTLS When Connecting to Mail Server

[skuddle]

I've been using Thunderbird since March 2017 and the last time was November 10. Today (November 11) I opened TB and everytime I try to send a message I receive the following message:

"Sending of the message failed.

"An error occurred while sending mail: Unable to establish a secure link with Outgoing server (SMTP) mail.bresnan.net using STARTTLS since it doesn't advertise that feature. Switch off STARTTLS for that server or contact your service provider."

This has been happening all day. I changed my server settings from STARTTLS to SSL/TLS but still received the error message.

This occurs on two separate computers (both running TB). I did nothing from the time I put them to sleep until the time I reactivated them.What could be the problem

[DanRaisch]

I did nothing from the time I put them to sleep until the time I reactivated them.What could be the problem

In which case there may have been changes on the server side of the connection.

Try changing the Connection Security Setting to "None" and see if that permits Thunderbird to send messages.

[skuddle]

Thank you for your reply.

I just tried setting my account settings server settings security settings to "None" and I still get that message. I'll call the service provider and see what's happening.

[rsx11m]

Sometimes anti-virus software is interfering with connections. Check if you have something like "Scan outgoing e-mail messages" enabled and disable it (at least for testing, you definitely want incoming messages to be scanned).