Re: rmail-message-filter

[Richard M Stallman]

    rmail-message-filter is an option in rmail.el. Post-mbox, it does nothing.
    Previously, it was called:

     i) the very first time a message was shown.
    ii) when toggling the headers to the normal state, every time.

In other words, it was called whenever headers were pruned.

The analogous time to call it is whenever rmail-show-message
displays a message (except when it displays the whole header).