To add a private messaging system to my website where members can send and receive private messages to each other. Just like "[url removed, login to view]", or "[url removed, login to view]". All messages should be saved in database using PHP and mySql. Neither members should be able to delete any of the messages.
All messages should be time and date stamped.
There should be a tab on the top of member's profile to indicate the number of unread messages (1, 2, ..) and if you click on the tab, a drop down list of all messages with name and picture of sender along with a small portion of the message should appear.
I should be able to click on any of the messages from the list provided and response to their inquiries.
Members should be able to send and receive small files of .pdf and .txt .doc and pictures to each other.
In addition I would like the current site that I am working on to be redesigned so it would work on IOS and Android devices and phones.
Also to make the site responsive.