Hey Julianna, 

I'm not aware of any specific solution (though I'm sure there is one out there), but if I was going to do it I would just create a special landing page that used a custom contact form (plenty of WP plugins for that), and I would create fields so that people could add the person's name, email address, and a custom note. I would then manually send the info to that person. Might be a bit clunky but it would get the job done. This won't be a major part of your business in my opinion so I wouldn't over think it. It could be for a specific promotion or something, but because those are for a limited time manually processing these shouldn't be too much of an issue. That's my take anyway.