Xterminal on what?

You need to start over and tell us what your hardware is,
because you started this in TMO>Talk>Talk>Community.

Otherwise we could be discussing just about anything.

Assuming you mean the n900,
the email is modest
based on tinymail
which if you look at the (admittedly quite interesting) descriptions
would show you it is a hopeless situation.

I had an acquaintance from the UK who described such scenarios
as being painted with a MWS and I have no idea how to describe it otherwise.

{Take little bits and pieces and throw them together
in not necessarily in any rational type of sequence, on the fly,
and conditionally or maybe not,
depending on which way the wind is blowing and whether the day
of the week is an odd-numbered calendar day
and throw in some urandom bits, spew an email off to a server.}

If you are so lucky.

I use citadel in other places on other machines and am accustomed to better documentation
(like this bit on how to replace sendmail)

than the gibbering mess modest devolved into.
Your only hope is to try to install sendmail or some other app.