[alex@karpathos ~]$ telnet oxmail.ox.ac.uk 25
Trying 163.1.2.163...
Connected to oxmail.ox.ac.uk.
Escape character is '^]'.
220 relay5.mail.ox.ac.uk ESMTP Exim 4.74 Tue, 01 Mar 2011 12:41:43 +0000
EXPN somerandomstring@physics.ox.ac.uk
250 <somerandomstring@physics.ox.ac.uk>
EXPN somerandomstring@oucs.ox.ac.uk
553 somerandomstring@oucs.ox.ac.uk is undeliverable