Skip to main content

Data Synchronization - Overview

Our Office interface provides you with a number of different options for synchronizing your calendars, address book, e-mails, and files with your different devices. This overview is intended to help you select the right option for you. Here we list the synchronization methods for the different systems (though with some hard work, you may be able to find more… :-))

We recommend

using these data synchronization methods if possible:

  • E-mail: Using IMAP and SMTP with your e-mail program
  • Calendar and tasks: Using CalDAV with your calendar program
  • Address book: Using CardDAV with your address book program
  • Files: Using the Drive Client or the web interface

We also offer ActiveSync, which is easy to set up, but often causes problems. Some functions many be limited or unavailable depending on your version of mobile device. For example, sometimes multiple calendars or address books cannot be synchronized, e-mails may only be available for a limited time, or tasks may be synchronized without the specified times or repetitions. Note that ActiveSync was developed to transfer current information to mobile devices as quickly as possible. It is not designed to synchronize mailboxes with a large volume of e-mails or to keep old e-mails synchronized on a permanent basis. If you would like to keep a large amount of data or all of your data on your mobile device, use one of the recommended synchronization methods described above. Please note, that we cannot offer support for activesync problems.

Time periods and intervals

Different time periods and intervals are available, depending on the synchronization method you choose:


  • Past e-mails: Unlimited
  • Maximum number of e-mails: Unlimited


  • Past calendars: 30 year
  • Future calendars: 10 years


  • Addresses: No limitations


  • Past calendar: 3 years
  • Future calendar: 3 years
  • Addresses: Unlimited
  • Max. size of contact images: 36kB (see: Microsoft EAS specification)
  • Past e-mails: 18 months (Upcoming: 3 and 6 years)
  • Maximum number of e-mails: 500 per IMAP folder
  • Tasks: Times and repetitions may not be supported


  • Maximum file size: 1 GB

Please note that synchronized changes may not be displayed immediately on all devices. Some changes in the web interface are not visible until you have logged out and logged back in.

We have provided instructions for most of the systems here in our Help/FAQ section. We plan to add instructions for additional systems. If your system is not listed, read the instructions for your software and attempt to complete the setup using the settings for ‘other devices.’

Note: Please bear in mind that the Drive is available in the packages Secure Mail, Mail XL/XXL, Office XL/XXL and in the packages Standard and Premium.

Mac OS X

  • Addresses using CardDAV with
  • Calendar using CalDAV with
  • E-mail using IMAP, POP3, SMTP with Apple or Mozilla Thunderbird
  • Files using Drive Client for Mac

PC with Linux

  • Addresses using CardDAV with Evolution
  • Calendar using CalDAV with Evolution
  • E-mail using IMAP, POP3, SMTP Mozilla Thunderbird, KMail, or Evolution
  • Files using WebDAV

PC with Windows

  • E-mail, addresses and calendar using CalDAV-Synchronizer with Microsoft Outlook
  • E-mail using IMAP, POP3, SMTP with Microsoft Outlook or LiveMail, Mozilla Thunderbird
  • Files using Drive Client for Windows

Smartphone/tablet with Android

  • Addresses and calendar using CardDAV or ActiveSync
  • E-mail using IMAP, POP3, SMTP with K9-Mail, or ActiveSync
  • Files using Drive Client for Windows (Google PlayStore)

Smartphone/tablet with iOS

  • Addresses and calendar using CardDAV or ActiveSync
  • E-mail using IMAP, POP3, SMTP with, or ActiveSync
  • Files using Drive Client for iOS (Apple AppStore)

Other smartphones (untested)

  • Addresses and calendar using CardDAV or ActiveSync
  • E-mail using IMAP, POP3, SMTP, or ActiveSync