Thank you for your reply to my question. This is surprising, we thought it would be possible to register custom own domains to have kind of a grouping of our contacts and different sources. Could you please let me know the way to get a grouping into the contacts list? For example we will have contacts from O365 and from a zip file. In the Provider now we can see "All Contacts" but how could we implement sub categories like "All O365 Contacts", "All Zip Contacts" ... ? Thank you.