text links in newsletter

Can anyone tell me how to use css textlinks in newsletters.
As far as i know ( by testing) all kind of mail providers overrule these css
and color my links in there own site color.

I would like to use one a:link to work on all textlinks in my ezine, also the
one's my customers make for themsleves, without having to put some code in it.

Any help is very welcome

Koen