I want to implement a new feature on Dollar Hauler that would allow other members to see a list of members who have been paid with an amount next to it. As for the troubling part, could I allow any member to contact another through the site? They would not see any email address or names (only usernames) and the messages would be delivered like a support ticket in their inbox on the site. As far as I can tell, this shouldn't be a problem but I thought I'd get some advice before I have a potential lawsuit on my hands
You need to ask the members of your site for their permission to allow other members to contact them through email. Just like when you signed up for this forum it gave you the option to have other members contact you. If they say it's ok than your fine, otherwise it could be considered spam.
I would do something like whenever a member is eligible to be put on that list, send out an email to them asking them permission to be contacted by other members. That would be the best way to go about that and of course have all emails sent only to the site inbox, not a real mail inbox as it would get spammed non-stop I am sure.
You definately must ask each member for their consent before disclosing their username as this is still a form of personal identification. You could do a really simple 'please tick this box if you are happy for your username to be listed for other memebrs to see' type thing. It doesn't need to be anything complicated, just a simple means of obtaining each members consent so that you are legally protected because you have gained their permission. In future, each time you get a new member you could obtain the consent then like on an opt-in basis, this way you have more creative freedom if you wish to disclose their username to members in a different way.