sxbiff is xbiff with signals.

If your MUA doesn't have a spool/mailfile for xbiff to monitor,
you can use sxbiff instead:

$ kill -SIGUSR1 $(pidof sxbiff) # raise the mailbox flag
$ kill -SIGUSR2 $(pidof sxbiff) # lower the mailbox flag

Alternatively, clicking the sxbiff window while the flag is raised will
lower it.

BUILDING:

sxbiff requires X11's development headers. These are usually packaged
as libX11-dev or something similar.

Once the development headers are installed:

$ git clone https://github.com/woodruffw/sxbiff && cd sxbiff
$ make

RUNNING:

$ ./sxbiff

The -o (--ontop) flag keeps sxbiff on top of all other windows.
The -v (--version) flag gives version information.

sxbiff runs on $DISPLAY.

LICENSE:

sxbiff is licensed by William Woodruff under the MIT License.

The flagdown.xbm and flagup.xbm bitmaps are licensed by The Open Group et al.
under the X/MIT License.

Full terms can be found in the LICENSE file.