This is activated whenever you receive new mail (non-irc mail) or when you start up irc and you have mail. You can use this to replace the standard "*** You have new mail" banner with anything you like. The parameters for this function are:
$0 The number of new mail messages
$1 Total number of mail messages
On startup, new mail messages will be all messages found.
After that, for example if you had 2 messages and a new
message came in, new messages would be 1. Here are a few
examples of how to use this:
on ^MAIL 1 /echo *** You have $0 new mail message, total of $1
on ^MAIL * /echo *** You have $0 new mail messages, total of $1
These will display the number of new messages that arrive.
Here is another example:
on ^MAIL * /comment
This will disable the display of any message when you have
mail. Setting the MAIL variable to OFF will also have this
effect, but this will also disable the total mail messages
count in the status line.