1) access Open-Xchange web email
2) Click on tab Address Book
3) Select the contact list you want to export, and click next to the screen shot.
4) Click on the Export button
5) Export with vCard format (.vcf)
6) Log out and log back in to webmail, now select Horde webmail
7) Click on the Address Book tab then click on the Import/Export button.
8) Select vCard as the main file. Click on Select file under Import Address Book, then select the exported .vcf file
9) Click the NEXT button and the address book will be imported for Horde webmail.