In actual fact, no. Outlook (all versions) can not master either CardDAV standard (necessary to synchronise contacts) or CalDAV standard (necessary to synchronise calendar entries).
Until recently (August 2014) it was possible to synchronise Posteo contacts with Outlook using a program called iCal4OL (after purchase). Unfortunately, the program is no longer available for purchase. If you already possess the discontinued program iCal4OL, the instructions found at the bottom of this page still apply for you.
At present, we know of the following alternatives:
- Bynari (requires purchase)
- cfos (free)
- OutlookDAV (requires purchase)
OutlookDAV performed best when we tested these programs. We are therefore providing detailed instructions for OutlookDAV:
Download the program from the provider’s website
- Start the SurGate OutlookDAV Client.
- Click on “Home”→“Basic”.
- For the Hostname, enter “posteo.de”, for the port, enter “8443”.
- For the Username and Password enter your Posteo email address (email@example.com) and password.
- Place ticks next to “Use SSL” and “Remember Me”.
- Click “Connect”.
- On the following screen, you can choose which Outlook folder each of Task, Calendar, and Contact should be synchronised with. As an example, we have chosen the standard folder for each.
- If you use multiple calendars, set up Outlook folders for each respective calendar.
- Click “Save” and in the next dialogue box click “OK”.
- Start the synchronisation by clicking the “Sync” button.
SurGate OutlookDAV Client is now running in the background and synchronises the information with our server at regular intervals.
Visual instructions: SurGate Outlook DAV
Sync with iCal4OL (only for existing users)
Here are instructions to set up the iCal4OL program:
- Start iCal4OL.
- Next to “Autoconfigure CalDAV for:”, click on “Other”.
- Next to “Server”, enter “posteo.de:8443”. For “Login” enter your Posteo address (firstname.lastname@example.org) and for “Password”, your Posteo password. Finally, confirm by clicking on “Retrieve settings from server and save.”
- The program now searches and finds the details for the settings that need to be changed.
- On the configuration page, next to “Who”, change your username to your Posteo email address and set the correct timezone.
- Then, on the configuration page, click “How”, and next to “Identification” replace everything that exists with “caldav deleted remove firstsimilar organizer multiget older href carddav singlecontacts no_auth”.
- Now go to the configuration page for “Contacts” and click “Synchronise with CardDAV”.
- On the page that appears, delete the tick next to “Only contacts changed since” and place a tick next to “Automatically with calendar synchronisation”, and then remove the tick next to “Only every sixth time”.
- Click “Exit”.
- Last of all, from the configuration site choose “Start” and decide (on the right hand side) what you would like to set the start and refresh options to.
- To finish, click “Start synchronisation” to initiate a first sync, and then on “Save”, and then the small arrow on the left next to “At the next restart” to activate and minimise the program.