#### Specifying Mailboxes to Operate Upon ¶

There are four basic ways of passing mailboxes to `guimb`.

`guimb [options] [mailbox...]`

  The resulting mailbox is not saved, unless the user-supplied scheme program saves it.

`guimb [options] --mailbox defmbox`

  The contents of defmbox is processed and is replaced with the resulting mailbox contents. Useful for applying filters to user’s mailbox.

`guimb [options] --mailbox defmbox mailbox [mailbox...]`

  The contents of specified mailboxes is processed, and the resulting mailbox contents is appended to defmbox.

`guimb [options] --user username [mailbox...]`

  The contents of specified mailboxes is processed, and the resulting mailbox contents is appended to the user’s system mailbox. This makes it possible to use `guimb` as a mail delivery agent.

If no mailboxes are specified in the command line, `guimb` reads and processes the system mailbox of the current user.