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. On behalf of the XYZ and the XYZ Organizing Committee, we are honored to invite you to speak at the XYZ event celebrating Cybersecurity Career Week (CCW).Invitation Letter for the Speaker - Free download as Word Doc (. Begin with a Polite Greeting. - In the opening paragraph, briefly introduce yourself and state the purpose of the letter. 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. I hope this letter finds you well. Sample Template for Inviting a Guest Speaker. In this section, we provide you with FREE Thanksgiving invitation letter templates for you to use during the holiday.