When wodMailbox opens and lock mailbox file, it will
just parse it to count total number of messages and get
starting and ending positions for each message. After that,
when you actually access message it will load it to memory
(or just part of it needed) and you will able to access
it's content.
If you make a changes, depending on AutoUpdate
property wodMailbox may save changes to mailbox file, or
just keep them in memory until you manually call Update
method. I suggest setting AutoUpdate property to
False and calling Update manually whenever you
make some change on mailbox. This way, you will be able to
make as many changes as needed, and Update it once. Check
out AutoUpdate to see what happens if you set it to
True, just to realize what to expect that way.
Warning: if you set AutoUpdate to
False and forget about calling Update method, your
changes will not be saved. This is normal behavior allowing
you to abandon your changes. For example, if you make some
change to the message and want to abandon changes, just
Unload that message and Load it again. This way Message
object is recreated with contents of mailbox. Your changes
are discarded.