Get online support
Can't receive or send emails with Thunderbird
Sending of the message failed.
Peer reports incompatible or unsupported protocol version.
The configuration related to smtp.tpg.com.au must be corrected.
Hi uluvit13.
A moderator produced this article for Thunderbird.
You'll notice near the end that SSL is set to NONE, so all communication is not encrypted. Thunderbird v78 has deprecated SSL/TLS below TLSv1.2.
If you want to use encryption, have a look here:
Read through the whole lot but take note at the end from David1010. I don't use Thunderbird so I can't comment on it.