EMail Plugin (friendica) Open Source Social Media

What I have: - a homemade, quite simple, private social-media system on a server of a friend, used by about 50 people (10 people regularly, rest only sometimes) - a mail-server, so it's possible to send and receive emails Now I want to migrate the network to the friendica system (see [login to view URL] for more information)! I will set up a friendica server myself, so it's possible to connect our network to the friendica network! The only problem is that by now the friendica mail-plugin has a couple of restrictions... What I want: 1. A mail-plugin with: (highest priority) - a seamless mail integration into friendica, which provides the possibility to send and receive emails, just as normal internal messages - support for html mails - support for mail attachments - some kind of email adressbook inside friendica and import/export possibility - possibility to use POP3 or IMAP for the emails - no problems with special letters (like ü,ö,ø,å, etc) 2. A nice, modern theme that resembles the old site (can be done when the rest is ready). I will provide some pictures for this task. 3. A plugin which allows people to send out invitations to new users, who can join without approval (optional) The code is supposed to be opensource and if any external code is used that should be opensource as well!