When you no longer need to keep a message, you can delete it. This flags it as ignorable, and some IMAIL commands pretend it is no longer present; but it still has its place in the IMAIL folder, and still has its message number.
Expunging the IMAIL folder actually removes the deleted messages. The remaining messages are renumbered consecutively. Expunging is the only action that changes the message number of any message.
There are two IMAIL commands for deleting messages. Both
delete the current message and select another message. d
imail-delete-forward) moves to the following message, skipping
messages already deleted, while C-d (
moves to the previous nondeleted message. If there is no nondeleted
message to move to in the specified direction, the message that was just
deleted remains current. A numeric argument to either command reverses
the direction of motion after deletion.
To make all the deleted messages finally vanish from the IMAIL
folder, type x (
imail-expunge). Until you do this, you can
still undelete the deleted messages. The undeletion command,
imail-undelete-previous-message), is designed to cancel
the effect of a d command in most cases. It undeletes the current
message if the current message is deleted. Otherwise it moves backward
to previous messages until a deleted message is found, and undeletes
imail-expunge irreversibly deletes mail, IMAIL
normally requires confirmation before it performs the expunge. This
confirmation is controlled by the value of the variable
imail-expunge-confirmation, which is a list of symbols. There
are two independent behaviors controlled by this: whether to prompt, and
whether to show the messages being expunged. If the list contains the
verbose (the default), the user is prompted for a
yes-or-no style confirmation; if the list contains the symbol
brief, the user is prompted for a y-or-n style confirmation; if
neither of these symbols is present, no confirmation is done. If the
list contains the symbol
show-messages, a window is popped up
showing the messages to be expunged; otherwise the list is not shown.
You can usually undo a d with a u because the u moves back to and undeletes the message that the d deleted. But this does not work when the d skips a few already-deleted messages that follow the message being deleted; then the u command undeletes the last of the messages that were skipped. There is no clean way to avoid this problem. However, by repeating the u command, you can eventually get back to the message that you intend to undelete. You can also select a particular deleted message with the M-p command, then type u to undelete it.
A deleted message has the `deleted' flag, and as a result `deleted' appears in the mode line when the current message is deleted. In fact, deleting or undeleting a message is nothing more than adding or removing this flag. See Flags.