A couple of things I'd ask you to do:

1. Include a copy of this notice on your product website (similar to the notice on the reMail HP)
2. Please include credit like "Based on reMail, an open source project by Google, Inc." somewhere inside the product (right now it's in AboutViewController)
3. In Xcode, do an Edit > Find > Find in Project, and search for "support@yourcompany.com". Replace each occurrence with your support email address.