With v78.6.0 I get a message of connection refused when connecting to localhost port 2110, which is the local end of an ssh tunnel to a pop3 server. Previous versions of thunderbird have worked well. Telnetting to the tunnel connects to the pop server so the problem is not the tunnel. Using tcpflow i see the destination port of the connections to be 2080 instead of 2110. I tried changing the port number to 2140 but still get 2080 as the destination port with tcpflow. Changing the local port to 2080 for the tunnel makes the connection, tcpflow shows the server response, but thunderbird still gives the connection refused message. Thanks for any help.