In PMMail-> Global Settings-> Secure Transfer is it enabled? Is it running? You do need to close the program, and start it again, to get it to run. It must be running to do the setup.
Check your entries (I didn't go through the pictures that were posted). It should all make sense. The local side uses localhost to talk to STunnel, which uses the given ports to talk to the remote host. The server address is used to relate the Account settings to the server settings.
Then, in each account, you need the server address, and logon information. You need to enable "Use Secure Channel (SSL)" so PMMail knows to use localhost rather than then the server address. Then you need the matching port. The ports associate what STunnel does. Looking at the pictures, I would not use port 995 for the local port. Use 110 in both the STunnel setup, and the account receive settings.
If you use STunnel with more than one mail server, you need to modify the local ports so they are not the same as what is used with a different mail server. Otherwise, STunnel can't tell the difference. What I do, is add 6, or 7, in front of the port numbers, and change all applicable settings.
Difficult to explain, but actually quite logical, after you figure it out.