I'm looking at your log file there, and I'm noticing something weird. You said that the log starts after the TLS connection is already established, but I read in one of the RFCs that the server MUST NOT send 250-STARTTLS if the TLS connection already exists. I wonder if gmail follows that portion of the SMTP protocol properly, or if the google programmers have created their own gSMTP protocol.... I don't have access to any other TLS-enabled SMTP servers, but it might be interesting to try the connection on one that isn't gmail.

-genius_at_work