I have the same issue, except I am trying use an internal mailbox:
Using the IP address, I get:
Failed to connect: No authentication mechansims supported by both server and client
DEBUG: setDebug: JavaMail version 1.4.5
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "xxx.xxx.xxx.xxx", port 25, isSSL false
220 SERVER.hsy.local Microsoft ESMTP MAIL Service ready at Thu, 18 Sep 2014 09:19:31 +1000
DEBUG SMTP: connected to host "xxx.xxx.xxx.xxx", port: 25
EHLO localhost.localdom
250-SERVER.hsy.local Hello [xxx.xxx.xxx.xxx]
250-SIZE 41943040
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-AUTH
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 XEXCH50
DEBUG SMTP: Found extension "SIZE", arg "41943040"
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "AUTH", arg ""
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "BINARYMIME", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "XEXCH50", arg ""
DEBUG SMTP: Attempt to authenticate
DEBUG SMTP: check mechanisms: LOGIN PLAIN DIGEST-MD5 NTLM
DEBUG SMTP: mechanism LOGIN not supported by server
DEBUG SMTP: mechanism PLAIN not supported by server
DEBUG SMTP: mechanism DIGEST-MD5 not supported by server
DEBUG SMTP: mechanism NTLM not supported by server
If I use the FQDN, I get the same thing.