Helen,

> I use XanaNews and it's impossible for me to post to the lists
> from there, because it insists on using my default email address

(which is

> not the email address I use on the lists).

You can create new identities in XanaNews and associate them with an
account or newsgroup. This does work as I use them for other servers.
I though this issue maybe a XanaNews issue, but I have tried with a
couple of other newsreaders and messages from them don't come through
either.

Phil