just curious if there any tool that I can just give a mail server address/ip to and that would give me all features that mail server supports.
Like: does it support imap/pop3? Does it support tls/ssl/ntlm encryption? etc....
Services can usually be determined by a quick port scan, but this can (and should) trigger any decent IDS into shutting you out of the network completely.
For checking the authentication methods, a simple EHLO should list the relevant details:
C:\Users\mark.henderson>telnet enetsxs1 25 220 enetsxs1.com.au Microsoft ESMTP MAIL Service ready at Wed, 9 Feb 2011 15:42:09 +1100 ehlo 250-enetsxs1.com.au Hello [192.168.161.140] 250-SIZE 10485760 250-PIPELINING 250-DSN 250-ENHANCEDSTATUSCODES 250-AUTH NTLM LOGIN 250-8BITMIME 250-BINARYMIME 250 CHUNKING