<s>
The	O
ancestor	O
of	O
sendmail	B-Application
,	O
delivermail	B-Protocol
,	O
also	O
by	O
Eric	O
Allman	O
,	O
is	O
a	O
mail	B-Protocol
transport	I-Protocol
agent	I-Protocol
that	O
used	O
the	O
FTP	B-Protocol
protocol	O
on	O
the	O
early	O
ARPANET	O
to	O
transmit	O
e-mail	O
to	O
the	O
recipient	O
.	O
</s>
<s>
Due	O
to	O
deficiencies	O
in	O
using	O
FTP	B-Protocol
to	O
send	O
e-mail	O
,	O
a	O
new	O
protocol	O
was	O
created	O
in	O
1981	O
for	O
sending	O
e-mail	O
,	O
SMTP	B-Protocol
.	O
</s>
<s>
After	O
DNS	B-Protocol
replaced	O
hosts	B-Protocol
files	I-Protocol
,	O
DNS-style	O
host	O
names	O
were	O
also	O
adopted	O
.	O
</s>
<s>
In	O
1979	O
,	O
when	O
delivermail	B-Protocol
was	O
first	O
shipped	O
with	O
4.0BSD	B-Operating_System
and	I-Operating_System
4.1BSD	I-Operating_System
,	O
the	O
ARPANET	O
was	O
still	O
using	O
NCP	B-Protocol
as	O
its	O
network	O
protocol	O
.	O
</s>
<s>
When	O
the	O
ARPANET	O
switched	O
to	O
TCP/IP	B-Protocol
at	O
the	O
end	O
of	O
1982	O
,	O
the	O
road	O
was	O
paved	O
for	O
MTAs	O
which	O
used	O
TCP	O
to	O
deliver	O
e-mail	O
;	O
delivermail	B-Protocol
evolved	O
into	O
sendmail	B-Application
.	O
</s>
