email whitelist suggestions

[David Banning]

I changed the IP address for my server recently having changed my ISP, and now mail from my server is getting continuously filtered into peoples spam folders.
 
I check my ip address on mxtoolbox.com fairly regularly - my IP never appears on a blacklist.

So now I'm thinking whitelist - but I don't have the money to lay out for this type of thing - at least not a large amount.

Anyone have a suggestion as to how to resolve my problem?