With servermx.com you have SOGo (www.sogo.nu) which supports CalDav and CardDav.
CardDav and CalDav enable to access online contact and calendar information.
Android can be easily configured to synchronize your Calendar/Address Book with your servermx.com Email account
How to set up CalDAV, CardDAV for Android
set protocol ssl with your username and password
For android can be used the following clients calDAV
DAVdroid – CalDAV/CardDAV Sync
DAVdroid is the all-in-one synchronization solution for both contacts (CardDAV) and calendars (CalDAV).
and for your contact client cardDAV (dmfs.org/carddav)