<s>
This	O
article	O
provides	O
a	O
list	O
of	O
software	O
products	O
and	O
cloud-based	B-Architecture
services	O
used	O
for	O
email	O
archiving	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
preservation	O
of	O
historical	O
records	O
may	O
require	O
a	O
one-time	O
migration	B-General_Concept
(	O
change	O
of	O
format	O
)	O
and	O
storage	O
,	O
while	O
regulatory	O
compliance	O
generally	O
calls	O
for	O
the	O
systematic	O
and	O
continuous	O
archival	O
of	O
messages	O
,	O
using	O
a	O
solution	O
that	O
provides	O
storage	O
and	O
retrieval	O
of	O
email	O
over	O
extended	O
time	O
periods	O
.	O
</s>
<s>
They	O
may	O
be	O
offered	O
as	O
a	O
standalone	O
computer	B-Architecture
appliance	I-Architecture
(	O
possibly	O
in	O
the	O
form	O
of	O
a	O
virtual	B-Application
machine	I-Application
)	O
,	O
as	O
installable	O
software	O
that	O
can	O
be	O
deployed	O
on	O
the	O
user	O
's	O
premises	O
,	O
or	O
as	O
a	O
cloud-based	B-Architecture
service	B-Architecture
.	O
</s>
<s>
They	O
may	O
work	O
with	O
a	O
variety	O
of	O
email	O
data	O
sources	O
(	O
email	O
systems	O
and	O
email	O
storage	O
file	O
formats	O
)	O
and	O
they	O
may	O
also	O
support	O
other	O
types	O
of	O
messaging	O
systems	O
such	O
as	O
social	O
media	O
or	O
instant	B-Application
messaging	I-Application
.	O
</s>
<s>
Additionally	O
,	O
several	O
collaborative	B-Application
software	I-Application
products	O
(	O
which	O
commonly	O
have	O
messaging	O
components	O
)	O
can	O
also	O
archive	B-Application
the	O
data	O
that	O
they	O
manage	O
;	O
however	O
,	O
those	O
systems	O
are	O
not	O
listed	O
here	O
since	O
they	O
generally	O
do	O
not	O
archive	B-Application
third-party	O
email	O
data	O
.	O
</s>
<s>
In	O
addition	O
to	O
a	O
backup	B-Protocol
system	O
,	O
several	O
other	O
components	O
are	O
necessary	O
for	O
a	O
useful	O
email	O
archiving	O
system	O
:	O
</s>
