Google Contacts, the address book built into Gmail, lets you keep track of all your contacts, see when you last interacted with them, and more.
Send approved customer updates by name and track failed sends.
Your usable contacts get personalized emails, and you get a clear report of every send, skip, and failure.
Send approved customer updates and flag incomplete contact details.
Your group mailing goes out from the team mailbox, with duplicate addresses skipped and a reply showing sends and exceptions.