<s>
SquirrelMail	B-Language
is	O
a	O
project	O
that	O
aims	O
to	O
provide	O
both	O
a	O
web-based	B-Protocol
email	I-Protocol
client	I-Protocol
and	O
a	O
proxy	B-Application
server	I-Application
for	O
the	O
IMAP	B-Protocol
protocol	O
.	O
</s>
<s>
The	O
latest	O
stable	O
version	O
1.4.23-svn	O
is	O
tested	O
with	O
PHP	B-Application
up	O
to	O
version	O
8.1	O
and	O
replaces	O
version	O
1.4.22	O
which	O
can	O
only	O
run	O
on	O
PHP	B-Application
version	O
5.0-5.4	O
.	O
</s>
<s>
The	O
svn	B-Application
part	O
in	O
the	O
version	O
name	O
points	O
out	O
that	O
bugfixes	O
and	O
minor	O
improvements	O
are	O
no	O
longer	O
published	O
as	O
new	O
versions	O
,	O
but	O
instead	O
are	O
maintained	O
within	O
Apache	B-Application
Subversion	I-Application
version	O
control	O
system	O
.	O
</s>
<s>
The	O
webmail	B-Protocol
portion	O
of	O
the	O
project	O
was	O
started	O
by	O
Nathan	O
and	O
Luke	O
Ehresman	O
in	O
1999	O
and	O
is	O
written	O
in	O
PHP	B-Application
.	O
</s>
<s>
SquirrelMail	B-Language
can	O
be	O
employed	O
in	O
conjunction	O
with	O
a	O
LAMP	B-Application
"	I-Application
stack	I-Application
"	I-Application
,	O
and	O
any	O
other	O
operating	O
systems	O
that	O
support	O
PHP	B-Application
are	O
supported	O
as	O
well	O
.	O
</s>
<s>
The	O
web	O
server	O
needs	O
access	O
to	O
the	O
IMAP	B-Protocol
server	I-Protocol
hosting	O
the	O
email	O
and	O
to	O
an	O
SMTP	B-Protocol
server	I-Protocol
to	O
be	O
able	O
to	O
send	O
mails	O
.	O
</s>
<s>
SquirrelMail	B-Language
webmail	B-Protocol
outputs	O
valid	O
HTML	B-Language
4.0	I-Language
for	O
its	O
presentation	O
,	O
making	O
it	O
compatible	O
with	O
a	O
majority	O
of	O
current	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
SquirrelMail	B-Language
webmail	B-Protocol
uses	O
a	O
plugin	B-Application
architecture	O
to	O
accommodate	O
additional	O
features	O
around	O
the	O
core	O
application	O
,	O
and	O
over	O
200	O
plugins	B-Application
are	O
available	O
on	O
the	O
SquirrelMail	B-Language
website	O
.	O
</s>
<s>
The	O
SquirrelMail	B-Language
IMAP	B-Protocol
proxy	B-Application
server	I-Application
product	O
was	O
created	O
in	O
2002	O
by	O
Dave	O
McMurtrie	O
while	O
at	O
the	O
University	O
of	O
Pittsburgh	O
(	O
where	O
it	O
was	O
named	O
"	O
up-imapproxy	O
"	O
,	O
although	O
it	O
has	O
become	O
more	O
commonly	O
known	O
as	O
"	O
imapproxy	O
"	O
)	O
and	O
adopted	O
by	O
the	O
SquirrelMail	B-Language
team	O
in	O
2010	O
.	O
</s>
<s>
It	O
is	O
written	O
in	O
C	B-Language
and	O
is	O
primarily	O
made	O
to	O
provide	O
stateful	B-Application
connections	O
for	O
stateless	B-Protocol
webmail	B-Protocol
client	O
software	O
to	O
an	O
IMAP	B-Protocol
server	I-Protocol
,	O
thus	O
avoiding	O
new	O
IMAP	B-Protocol
logins	O
for	O
every	O
client	O
action	O
and	O
in	O
some	O
cases	O
significantly	O
improving	O
webmail	B-Protocol
performance	O
.	O
</s>
<s>
Both	O
SquirrelMail	B-Language
products	O
are	O
free	B-License
and	I-License
open-source	I-License
software	I-License
subject	O
to	O
the	O
terms	O
of	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>
SquirrelMail	B-Language
webmail	B-Protocol
is	O
available	O
for	O
any	O
platform	O
supporting	O
PHP	B-Application
.	O
</s>
<s>
Most	O
commonly	O
used	O
platforms	O
include	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
,	O
macOS	B-Application
and	O
the	O
server	O
variants	O
of	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
SquirrelMail	B-Language
IMAP	B-Protocol
Proxy	O
compiles	O
on	O
most	O
flavors	O
of	O
Unix	B-Application
,	O
and	O
can	O
generally	O
be	O
used	O
on	O
the	O
same	O
platforms	O
that	O
the	O
webmail	B-Protocol
product	O
can	O
with	O
the	O
exception	O
of	O
Microsoft	B-Application
Windows	I-Application
,	O
unless	O
used	O
in	O
a	O
Cygwin	B-Language
or	O
similar	O
environment	O
.	O
</s>
<s>
Apple	O
shipped	O
SquirrelMail	B-Language
as	O
their	O
supported	O
web	B-Protocol
mail	I-Protocol
solution	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
Server	I-Operating_System
.	O
</s>
<s>
The	O
SquirrelMail	B-Language
webmail	B-Protocol
client	O
itself	O
is	O
a	O
complete	O
webmail	B-Protocol
system	O
,	O
but	O
extra	O
features	O
are	O
available	O
in	O
the	O
form	O
of	O
plugins	B-Application
.	O
</s>
<s>
There	O
are	O
over	O
200	O
third-party	O
plugins	B-Application
available	O
for	O
download	O
from	O
the	O
SquirrelMail	B-Language
website	O
and	O
SquirrelMail	B-Language
ships	O
with	O
several	O
"	O
standard	O
"	O
or	O
"	O
core	O
"	O
plugins	B-Application
.	O
</s>
<s>
SquirrelMail	B-Language
webmail	B-Protocol
has	O
been	O
translated	O
into	O
over	O
50	O
languages	O
including	O
Arabic	O
,	O
Chinese	O
,	O
French	O
,	O
German	O
,	O
and	O
Spanish	O
.	O
</s>
<s>
SquirrelMail	B-Language
has	O
been	O
implemented	O
as	O
the	O
official	O
email	O
system	O
of	O
the	O
Prime	O
Minister	O
's	O
Office	O
of	O
the	O
Republic	O
of	O
India	O
for	O
its	O
security	O
advantages	O
over	O
Microsoft	O
's	O
Outlook	B-Application
Express	I-Application
.	O
</s>
<s>
In	O
2004	O
HEC	O
Montréal	O
business	O
school	O
deployed	O
SquirrelMail	B-Language
as	O
part	O
of	O
a	O
comprehensive	O
webmail	B-Protocol
solution	O
,	O
to	O
support	O
thousands	O
of	O
users	O
.	O
</s>
