I am looking for a PHP based messaging portal.
Client 1 logins to portal sends a message to Recipient 1 (they may choose from a drop down box)
Recipient 1 gets an e-mail stating there is an message awaiting for them in the portal (no part of the actual message is contained in the portal)
Recipient 1 logs in and see's their list of messages, along with archives, history of messages for Client 1 who sent the message.
Recipient 1 is able to make internal notes as well and attach them to Client 1 only.
Recipient 1 replies to the message and Client 1 receives an e-mail stating they have a message awaiting them in the portal.
Client 1 logins and sees their list of current and past replies, and is able to reply, archive, or simply read without reply.
Recipient 1 is able to login and see if they've logged in and have read the message or not (notification is not needed but if a option can be added for their choice it would be better).
This would need to be MySQL based and easily brand-able along with MySQL data being encrypted.
An installer would be nice in case of reinstall needed but configuration files, instructions, paths, permissions, etc would suffice.
Admin will add recipients and clients - there is no self registration. There should be an option to customize the fields about the client.