[Evolution] Looking for info on why all viewed mail from an imap server is also stored in a local file

[Stefanie Blackburn <Stefanie Blackburn Sun COM>]

In using evolution 1.2.1 I noticed that all messages that I view on my
IMAP server are also stored locally under the following directory:

~/evolution/mail/imap/id mail server net/folders/
then under the corresponding mail folder such as INBOX

in looking at this I see the following entries:

drwx------   2 id staff        512 Jan  9 10:43 .
-rw-------   1 id staff     127896 Jan  9 10:43 summary
-rw-------   1 id staff       2442 Jan  9 09:45 15552.
-rw-------   1 id staff       1661 Jan  9 09:38 15647.
-rw-------   1 id staff       3840 Jan  9 09:36 15646.
drwx------   6 id staff        512 Jan  9 09:36 ..
-rw-------   1 id staff       1560 Jan  9 09:33 15645.
-rw-------   1 id staff       4906 Jan  9 09:33 15644.1
-rw-------   1 id staff       2151 Jan  9 09:32 15644.HEADER
-rw-------   1 id staff       2282 Jan  9 09:32 15643.
-rw-------   1 id staff       9888 Jan  9 09:00 15642.1
-rw-------   1 id staff       1056 Jan  9 09:00 15642.HEADER
-rw-------   1 id staff       5174 Jan  9 08:59 15641.1
-rw-------   1 id staff       2546 Jan  9 08:59 15641.HEADER
-rw-------   1 id staff       4580 Jan  9 08:59 15640.
-rw-------   1 id staff       1801 Jan  9 08:58 15639.
-rw-------   1 id staff       3677 Jan  9 08:58 15638.


Is this required/expected behaviour of Evolution? and if it is - Is
there a way to modify a setting so that message information is not
stored locally?

Thanks in advance