Probably overkill for your needs, but I use CiviCRM (https://civicrm.org) to do that for my work. It's basically a centralized web-based contact list, for which you can then link them between each other (different types of relations), add custom fields, etc. -- the program does a lot more than that (online fundraising, mass mail, event management, and other tools mostly aimed for non-profits/volunteer groups), but you can also just use it for that.
It's then possible to expose the contact data to LDAP using "ldapcivi" (https://github.com/TechToThePeople/ldapcivi), so that the contact data can be queried from any mail client (including phones).
We also integrated CiviCRM with our IRC bot, so we can query emails and other info from there. Ex: "who is John Doe" on irc will respond with the basic data (name, email, phone), as well as the relationships of that contact, ex: "John is Manager of foo at ACME".
It's then possible to expose the contact data to LDAP using "ldapcivi" (https://github.com/TechToThePeople/ldapcivi), so that the contact data can be queried from any mail client (including phones).
We also integrated CiviCRM with our IRC bot, so we can query emails and other info from there. Ex: "who is John Doe" on irc will respond with the basic data (name, email, phone), as well as the relationships of that contact, ex: "John is Manager of foo at ACME".