<s>
K-9	B-Application
Mail	I-Application
is	O
free	B-License
and	I-License
open	I-License
source	I-License
email	B-Protocol
client	I-Protocol
for	O
Android	B-Application
.	O
</s>
<s>
It	O
is	O
designed	O
as	O
an	O
alternative	O
to	O
the	O
stock	O
email	B-Protocol
clients	I-Protocol
included	O
with	O
the	O
platform	O
;	O
it	O
supports	O
both	O
POP3	B-Protocol
and	O
IMAP	B-Protocol
protocols	O
and	O
supports	O
IMAP	B-Protocol
IDLE	I-Protocol
for	O
real-time	O
notifications	O
.	O
</s>
<s>
On	O
13	O
June	O
2022	O
,	O
it	O
was	O
announced	O
that	O
K-9	B-Application
Mail	I-Application
had	O
been	O
taken	O
over	O
by	O
MZLA	O
Technologies	O
Corporation	O
,	O
a	O
subsidiary	O
of	O
the	B-Operating_System
Mozilla	I-Operating_System
Foundation	I-Operating_System
with	O
current	O
maintainer	O
Christian	O
Ketterer	O
joining	O
the	O
team	O
,	O
and	O
plans	O
for	O
K-9	B-Application
Mail	I-Application
to	O
be	O
rebranded	O
as	O
Thunderbird	B-Application
for	O
Android	B-Application
following	O
the	O
completion	O
of	O
a	O
feature	O
roadmap	O
,	O
including	O
sync	O
with	O
Thunderbird	B-Application
on	O
PC	O
,	O
integrating	O
Thunderbird	B-Application
's	O
automated	O
account	O
setup	O
system	O
,	O
message	O
filtering	O
,	O
and	O
improvements	O
to	O
folders	O
.	O
</s>
<s>
This	O
application	O
has	O
been	O
downloaded	O
from	O
the	O
Google	B-Application
Play	I-Application
Store	I-Application
between	O
5	O
million	O
and	O
10	O
million	O
times	O
since	O
its	O
release	O
and	O
has	O
been	O
rated	O
by	O
over	O
90,000	O
people	O
with	O
almost	O
as	O
many	O
1	O
star	O
reviews	O
as	O
5	O
star	O
reviews	O
many	O
due	O
to	O
the	O
fundamental	O
restructuring	O
of	O
the	O
program	O
in	O
August	O
2021	O
,	O
which	O
was	O
not	O
widely	O
accepted	O
by	O
the	O
user	O
base	O
and	O
more	O
recently	O
because	O
of	O
unacceptable	O
battery	O
usage	O
when	O
using	O
push	O
to	O
fetch	O
mail	O
.	O
</s>
