You should include the name of the host, formal expression, the event purpose, date, time, and venue, contact details, and RSVP. Learn how to write a professional and effective formal invitation letter sample for a seminar.Download this template now! The letter should be free, but you may need to register to the conference to convince people you are actually attending the conference. 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. We have curated 15 different templates for invitation letters that can help you write invitation letters with ease. This letter typically includes essential details like your name, the event dates, the venue, and a confirmation of your participation. In late September, the NACE Board of Directors held a twoday Strategic Planning workshop focusing on the future of NACE. SECONDED. Page 13. OCT. 23,1935. This annual event will bring together over 400 civil and environmental engineering students from the southeast region.