<s>
Mutt	B-Device
is	O
a	O
text-based	B-Protocol
email	I-Protocol
client	I-Protocol
for	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
It	O
was	O
originally	O
written	O
by	O
Michael	O
Elkins	O
in	O
1995	O
and	O
released	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
version	O
2	O
or	O
any	O
later	O
version	O
.	O
</s>
<s>
The	O
Mutt	B-Device
slogan	O
is	O
"	O
All	O
mail	B-Protocol
clients	I-Protocol
suck	O
.	O
</s>
<s>
Mutt	B-Device
supports	O
most	O
mail	O
storing	O
formats	O
(	O
notably	O
both	O
mbox	B-Application
and	O
Maildir	O
)	O
and	O
protocols	O
(	O
POP3	B-Protocol
,	O
IMAP	B-Protocol
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
It	O
also	O
includes	O
MIME	B-Protocol
support	O
,	O
notably	O
full	O
PGP/GPG	O
and	O
S/MIME	B-Protocol
integration	O
.	O
</s>
<s>
Mutt	B-Device
was	O
originally	O
designed	O
as	O
a	O
Mail	B-Protocol
User	I-Protocol
Agent	I-Protocol
(	O
MUA	O
)	O
and	O
relied	O
on	O
locally	O
accessible	O
mailbox	O
and	O
sendmail	B-Application
infrastructure	O
.	O
</s>
<s>
According	O
to	O
the	O
Mutt	B-Device
homepage	O
"	O
though	O
written	O
from	O
scratch	O
,	O
Mutt	B-Device
's	O
initial	O
interface	O
was	O
based	O
largely	O
on	O
the	O
ELM	B-Application
mail	I-Application
client	I-Application
"	O
.	O
</s>
<s>
New	O
to	O
Mutt	B-Device
were	O
message	O
scoring	O
and	O
threading	O
capabilities	O
.	O
</s>
<s>
Support	O
for	O
fetching	O
and	O
sending	O
email	O
via	O
various	O
protocols	O
such	O
as	O
POP3	B-Protocol
,	O
IMAP	B-Protocol
and	O
SMTP	B-Protocol
was	O
added	O
later	O
.	O
</s>
<s>
However	O
,	O
Mutt	B-Device
still	O
relies	O
on	O
external	O
tools	O
for	O
composing	O
and	O
filtering	O
messages	O
.	O
</s>
<s>
Mutt	B-Device
has	O
hundreds	O
of	O
configuration	O
directives	O
and	O
commands	O
.	O
</s>
<s>
Mutt	B-Device
supports	O
an	O
optional	O
sidebar	O
,	O
similar	O
to	O
those	O
often	O
found	O
in	O
graphical	B-Application
mail	B-Protocol
clients	I-Protocol
.	O
</s>
<s>
There	O
are	O
also	O
many	O
patches	O
and	O
extensions	O
available	O
that	O
add	O
functionality	O
,	O
such	O
as	O
NNTP	B-Protocol
support	O
.	O
</s>
<s>
Mutt	B-Device
is	O
fully	O
controlled	O
with	O
the	O
keyboard	O
,	O
and	O
has	O
support	O
for	O
mail	O
conversation	O
threading	O
,	O
meaning	O
one	O
can	O
easily	O
move	O
around	O
long	O
discussions	O
such	O
as	O
in	O
mailing	O
lists	O
.	O
</s>
<s>
New	O
messages	O
are	O
composed	O
with	O
an	O
external	O
text	B-Application
editor	I-Application
,	O
unlike	O
pine	B-Operating_System
,	O
which	O
embeds	O
its	O
own	O
editor	O
known	O
as	O
pico	B-Operating_System
.	O
</s>
<s>
Mutt	B-Device
is	O
capable	O
of	O
efficiently	O
searching	O
mail	O
stores	O
by	O
calling	O
on	O
mail	O
indexing	O
tools	O
such	O
as	O
Notmuch	O
,	O
and	O
many	O
people	O
recommend	O
Mutt	B-Device
be	O
used	O
this	O
way	O
.	O
</s>
<s>
Alternatively	O
,	O
users	O
can	O
search	O
their	O
mail	O
stores	O
from	O
Mutt	B-Device
by	O
calling	O
grep	B-Application
via	O
a	O
Bash	B-Operating_System
script	I-Operating_System
.	O
</s>
<s>
Mutt	B-Device
is	O
often	O
used	O
by	O
security	O
professionals	O
or	O
security-conscious	O
users	O
because	O
of	O
its	O
smaller	O
attack	O
surface	O
compared	O
with	O
other	O
clients	O
that	O
ship	O
with	O
a	O
web	B-Protocol
browser	I-Protocol
rendering	I-Protocol
engine	I-Protocol
or	O
a	O
JavaScript	B-Language
interpreter	O
.	O
</s>
<s>
In	O
relation	O
to	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
,	O
Mutt	B-Device
can	O
be	O
configured	O
to	O
trust	O
certificates	O
on	O
first	O
use	O
,	O
and	O
not	O
to	O
use	O
older	O
,	O
less	O
secure	O
versions	O
of	O
the	O
Transport	B-Protocol
Layer	I-Protocol
Security	I-Protocol
protocol	I-Protocol
.	O
</s>
