Hi,
aol and yahoo users not accepting mail and finally just removed them all from my list. Sometimes that is just the way things go.
Hardly the case, removing ALL of these users will reduce your list by half I would guess! Certainly it's much better to try to determine the reason why your emails are not getting through.
As suggested it may be because your host is on a blocked list, or that you are using words in your message that trigger the BULK MAIL filter at Yahoo or AOL.
The only way to guarantee delivery is to offer a White Listing page with detailed instructions on how others can add you to their own filters, or address book so that your email messages are delivered.
Good luck, if you find any enlightening news please let us know.