Utilities - mexpn

mexpn - prints out the mail alias expansion from a given mail server

mexpn prints out the mail alias expansion from a given mail server. This is useful to discover if a given mail address is valid or not. However, if you can not establish a connection (and many mail servers can not be accessed directly) then nothing can really be said one way or the other.

The hostname can be given as a host.domain name or as an IP address.