We use Zoho mail for shared contacts.
If you have sufficient privileges, then you have been added you to the Shared Contacts Group which you can find by going to the contacts icon on the far left of the page.
I think this might help solve the problem of a supplier list etc for us.
You can navigate to this list by by clicking on the small arrow at the side of shared contacts and then clicking on the specific group you want to use (ie supplier, contractor etc)
You can add to this list by either clicking the the + button at the top of the contact tab
or by moving one of your personal contacts into the Shared folder and then hitting the edit button:
If we do choose to use this then please have some sensible way of putting a note in about whether they are a preferred supplier or similar in the notes section.