Try this link http://trac.roundcube.net/wiki/Plugin_Repository
There is something interesting in Authentification part.
darren wrote:
==== Required information ====
- iRedMail version: 0.8.5
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: Ubuntu 12.04 LTS
- Related log if you're reporting an issue:
====Has anyone added two-factor authentication to iRedMail? Specifically for roundcube webmail, and the other tool that are accessible via the web?
I've started looking for a Roundcube plugin, but I wondered if I'm likely to hit any extra issues with using the LDAP backend, or trying to do this for the other tools like iRedAdmin?
Any pointers would be appreciated,