nonstandard screen size

[Jeff Williams]

I use a Psion S5 as a dumb terminal to connect to my office computer
(dialup), then invoke Mutt to check my email (using TERM=vt100).  The
problem is that the Psion screen, though it is supposed to be `vt100'
in most respects, is physically only 18 lines, and the display gets
scrambled.  How can I tell Mutt to work with an 18 line x 80 column
screen?  Thanks,

jtw