GMailify not available for Postfix based email account.

I have a hosted domain with email account with which the users want to use GMailify.  CentOS 7 is fully updated and I'm using CWP PRO.  I can send and receive email using Roundcube with no problems. 

When I attempt to link one of the Postfix email accounts to a GMail account using GMailify I get the following response from Gmail:
GMailify is not available for this provider.

Is this a standard problem with CWP or is it possibly a problem due to the rDNS and DMARK issues that remain?

Is it possible to link the accounts using GMailify?

Hi, GMailify is not CWP software. Try to check your software.