Safe e-mail

I need to setup an email for my grandmother.

Can I use spam assassin to blacklist all email except from people I have whitelisted?

Can I do this only on 1 email adrress without effecting any other's settings?

Thanks in advance!

I've never tried it on a shared host. But what I would try first is to put this in the one of the blacklist boxes:

*

That means block from everyone.

Then add some some whitelist addresses and test it out.

Let us know if it works.