When the target server responds to a "telnet“ on port 25 (SMTP), the command "ehlo“ is used to prove whether TLS is possible or not. When the server‘s response on „ehlo“ contains the phrase "STARTTLS" then the server itself confirms it is able to use TLS.
If TLS does not work in conjunction with Continuity Service the emails will never be delivered.
Here is the "telnet":
91.84.159.209 is the IP of the target server for Owlsworth / ijp.co.uk:
dns01-haj2:/ # telnet 91.84.159.209 25
Trying 91.84.159.209...
Connected to 91.84.159.209.
Escape character is '^]'.
220 portal.ijp.co.uk Microsoft ESMTP MAIL Service, Version: 6.0.3790.4675 ready at Tue, 11 Dec 2012 19:13:17 +0000
ehlo test
250-portal.ijp.co.uk Hello [83.246.65.151]
250-TURN
250-SIZE
250-ETRN
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-8bitmime
250-BINARYMIME
250-CHUNKING
250-VRFY
250-TLS
250-STARTTLS
250-X-EXPS GSSAPI NTLM LOGIN
250-X-EXPS=LOGIN
250-AUTH GSSAPI NTLM LOGIN
250-AUTH=LOGIN
250-X-LINK2STATE
250-XEXCH50
250 OK