telnet hostname 25
helo <senderdomain>
mail from: userid@domain.com
rcpt to: recipient_userid@domain.com
data
enter message, complete with to:, from:, and subject: .... finish with a "." on a line by itself
quit
telnet hostname 80
GET | HEAD [* | /dirname/filename] HTTP/1.0
return, twice.
This one is rather useful in determining what machine actually serves as
the mail relay for a domain.
Yes, I know that I could do this with dig....but hey, I'm old
fashioned that way....
nslookup
set query=mx | hinfo # MX returns the mail records, hinfo returns the host info record
domain.com