TELNET

telnet [-a][-e escape char][-f log file][-l user][-t term][host [port]]

-a Attempt automatic logon. Same as -l option except uses the currently logged on user's name.
-e Escape character to enter telnet client prompt.
-f File name for client side logging
-l Specifies the user name to log in with on the remote system.
Requires that the remote system support the TELNET ENVIRON option.
-t Specifies terminal type.
Supported term types are vt100, vt52, ansi and vtnt only.
hostSpecifies the hostname or IP address of the remote computer to connect to.
portSpecifies a port number or service name.

Examples

telnet maila.microsoft.com 25

More MX record testing

Associated Commands

NSLOOKUP