General
You have the option of integrating your mail.ch contacts into external address books. In this way you always keep your address book up to date, even if you manage it on different end devices with different programmes. The CardDAV protocol is used for this purpose. If an address book supports the CardDAV protocol, you can integrate and synchronise the mail.ch address book there.
Unfortunately, the CardDAV standard is not supported by all address books, as they have either implemented their own proprietary solution (Microsoft Outlook), or have not (yet) integrated a solution for integrating external contacts. In some cases, the installation of plug-ins or external apps that enable the CardDAV standard can help.
Note: Different address books do not always support all fields for a contact. This can lead to deviations in the display.
However, we recommend that you always define the first and last name for a contact in the mail.ch address book, as this is usually always supported. The field "Display name" is often not sufficient!