Hello,
We are not on the same page here as you are writing your own mail client so you should be able to debug it on your side in order to point where the problem is (if any).
We could continue our investigations if you could use the standard SSL client openssl (you should find a way to install it on your system - you may find some hints here) and show us the output from the following command:
openssl s_client -connect localhost:465 -crlf
HTH,
Ioan