heya sue
of course every service is set up a bit differently... a lot of ISP's do filtering for you just like the freebie services (yahoo, g, etc) - in either case, the "allow from" whitelist isn't going to be on YOUR end (ie, outlook express) but rather on the ISP end. If you have access to web-based mail with your ISP check there first for allow/deny lists. If it's mail on your hosting account, check CPanel (if you have it...)
My christmas gift to you => pm me if you need more specific help hehe
