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.

Connection string for Thunderbird

Connection strings for Apple Mac OS are:

Configuration details for Mac OS:

Account Type: Advanced

User name: {USER_MAIL_BOX}

Password: {yourpassword}

Server Address: https://sogo.servermx.com/SOGo/

Server path: https://sogo.servermx.com/SOGo/dav/{USER_MAIL_BOX}

Android can be easily configured to synchronize your Calendar/Address Book with your servermx.com Email account

For android can be used the following clients calDAV (dmfs.org/caldav)

CalDAV-Sync
JB Workaround CalDAV-Sync

SolCalendar - Android Calendar

SolCalendar

and for your contact client cardDAV (dmfs.org/carddav)

CardDAV-Sync
JB Workaround CardDAV-Sync

DAVdroid – CalDAV/CardDAV Sync
DAVdroid is the all-in-one synchronization solution for both contacts (CardDAV) and calendars (CalDAV).