<s>
mailx	B-Device
is	O
a	O
Unix	B-Application
utility	O
program	O
for	O
sending	O
and	O
receiving	O
mail	B-Protocol
,	O
also	O
known	O
as	O
a	O
Mail	B-Protocol
User	I-Protocol
Agent	I-Protocol
program	O
.	O
</s>
<s>
Being	O
a	O
console	B-Device
application	I-Device
with	O
a	O
command	O
syntax	O
similar	O
to	O
ed	B-Application
,	O
it	O
is	O
the	O
POSIX	O
standardized	O
variant	O
of	O
the	O
Berkeley	O
Mail	B-Protocol
utility	O
.	O
</s>
