You can use the Email Scheduler for Gmail to schedule birthday and anniversary greetings in advance, create recurring reminders (for events, employee appraisals, appointments), and more. The scheduler can also send recurring emails that go out automatically on daily, weekly, monthly or yearly repetitive schedule. You can write your messages now and Gmail will send them later at your specified date and time. Email Scheduler for Gmail lets you schedule email messages inside Gmail with the help of a Google Spreadsheet.