@Mattj Welcome to Community Forum. OfferUp app wouldn't allow to post your private information like emails, phone numbers or prohibited items. Be sure to check out OU's app guidelines and Community guidelines here.
Leaves comments share your ideas and give somes Kudos earns somes badges along the way. If you have specific questions would like to ask members about OC Forums by using tag @ in front of the username to get swift respond like I did to your name on top. What are you using OfferUp app for buying or selling?