Email Contacts

We continue to have issues with mail contacts. Migrated from gmail to Zoho and STILL CANNOT get contacts from gmail into my email account. When I try to import message received that contacts are ALREADY in my mail; they are not. When I click on an address in an email header and add the contact, the newly added contact is no where to be found. Groups set up and because NO ONE is familiar with ZOHO not accepting invitation and therefore 60% of the contacts in groups don't get the email. Can't create a list to send to in my own email with it being a GROUP which results in the same problem; people not accepting the invitation. WE MUST be able to communicate to our 200+ volunteers and email is one tool we use. Someone PLEASE help me resolve this.