Haven't found this on CampaignMonitor, but it would be good to have something we can link to like this one (I think it's from ExactTarget; it was used in an email from Adobe to me):
To help subscribers add us (whitelist us) to their address book, contacts, or safe sender list. Any problems with linking to the above page for now?
Hey there Jeremy, that's an excellent site! We really should come up with some whitelisting instructions like this, but by all means, use this link for now - it's got everything recipients need. Thanks for passing this on!