Funnel CRM is tightly tied to your Gmail or Google Apps account. You use it to sign up, and log in into the app, and also to receive notifications and replies from your customers.
When you receive a reply to a message you sent from Funnel CRM in your Gmail inbox, you can reply directly to that message from Gmail, and your reply will be sent to your customer, but it will also appear within your Funnel deal.
This is especially useful when you're on the go and don't want to mess around with logging in to another service only to send a quick reply, and would rather do it from your phone.
Funnel CRM can't access your email inbox.
Funnel CRM is not in any way affiliated with Google™. Funnel CRM uses Google's service to retreive your account information and to log you in securely. No one at Funnel CRM can access your inbox or any other part of your Google account.