Private messaging feature is one thing that Classipress is lacking. Currently, buyers can only be contacted by the seller through email and or through the other posted contact information such as phone numbers and etc. This is not a Classipress limitation but rather of the WordPress platform.
WordPress just does not allow your users to communicate with each other. Though you can use some forum plugins to add private messaging functionality but they are quite heavy specially if you don’t need a forum yet on your site. Also the updates might not be focused on improving the messaging features at all. Now, the lack of private messaging option has been answered by the WordPress User Messages plugin.
User Messages is a plugin that can facilitate communication between your users. It functions just like a normal private messaging system. It is available under the GPL license, which means that it’s free. All the instructions for installation, the support forums, a FAQ, etc. can be found here.
