Mail.app the most popular client, are you kidding? I don't think I even know a Mac user who uses it, and I'd remind you that you've already limited to Mac user

Mail.app the most popular client, are you kidding? I don't think I even know a Mac user who uses it, and I'd remind you that you've already limited to Mac users. Surely the most popular client is Gmail web? But Outlook, and iOS default even, presumably beat Mail.app by far too.