ubuntu - custom cms in php - adding email features - need a simple way

so i've got my cms seductiveapps.com, which is now fully switched to the free couchdb JSON db architecture, and now supports users, groups, and photo and html files stored by either a group or a user.

now i want (and need to, by government regulations) to add email functionality to this setup.

i've done some googling, and the smartest thing that i've seen is to use an LDAP server for your user database, and an SMTP and IMAP server for outgoing and incoming email.

that way, with a php library that can connect to an IMAP server, you could display emails in your own interface, which as you can see on my site, is necessary for my site. Things like semi-transparancy become a factor.

my question is :
what is the easiest install path for the LDAP + SMTP + IMAP servers, starting at a fresh ubuntu install with an ubuntu.com installation file downloaded today as well.
i also need tips on how to connect to, and administrate, each of these 3 servers, from PHP.
i also need tips on how to make sure my entire setup can not be abused to get my SMTP server on world-wide blacklists.

these email features are primarily needed to comply with the new local law to enable law-enforcement to communicate with people whose content they take offline due to that content violating the law (such as calls for terrorism, or weapons manufacturing manuals, stuff like that),
and all other normal email features between users and groups on the system - and the outside world.

 

My method is to install postfix on ubuntu. If the CMS can use phpmail or sendmail, then postfix can be configured to deliver mail to an external SMTP provider such as sendgrid.