Roundcube includes an address book / contacts manager. You can easily add and manage contacts, and you can import or export contact details as electronic business cards.
Like the Mail page, the Contact page has three panes:
You can add a new contact via the Create button. Alternatively, you can also click on the sender’s “from” address and select Add to address book.
You can import and export contacts. For importing contacts you can either use vCard or CSV files. vCard, or VCF, is a common standard for electronic business cards. Most email clients are able to import and export to the format.
If you want to migrate all your contacts, you can simply select all your contacts and click the Export button. This creates a single .vcf file which you can then use to import the contacts in another email client or application.