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