Roundcube is an open-source webmail solution, available to you for free. If you’re using this application, you can also easily back up and restore contacts.
Follow these steps –
To Backup all the contacts in Roundcube, follow the steps given below.
1) Log in to web mail and then select Roundcube.
2) Click the Address Book available at the right top.
3) Click the group or email account which you want to backup.
4) Click the backup icon (Blue in color) to generate the backup.
It will generate a cnf file which can be stored at the desired location.