We'll detail everything you need to know about how to invite a guest speaker, from the earliest planning stages to drafting a formal speaker invitation letter. You should include the name of the host, formal expression, the event purpose, date, time, and venue, contact details, and RSVP.Begin with a Polite Greeting. We have curated 15 different templates for invitation letters that can help you write invitation letters with ease. Your invitation should be a formal email (or letter). Outline the reasons why you've chosen them as the best person to speak at your event.