If you have more than a few contacts you want to add to your address book in roundcube, adding them manually can be a chore. Fortunately, roundcube includes an import option so that you can import your contacts easily.
Please note, at this time, roundcube only supports the vCard format. If you cannot export or save your contact list to a vCard format, save it as a CSV (comma separated values) file. Then use one of the many free programs available that will convert your CSV file to a vCard file. One example is the online tool: CSV to vCard.
Next, click on the Import contacts button
Click the browse button in the Import contacts screen, select your vCard file and click the Import button to import your contacts.
Once the import is complete you will receive notification of how many contacts were imported. Click the Done button to be returned to the Address Book screen where you can view and manage your newly imported contacts.