Due to 20th Anniversary of the Regional Centre of Manufacturing Systems Engineering (RCMSE), on this important opportunity the Centre would like to gladly invite ... as a guest speaker to give a special talk on "...(topic)..." at ...(venue)... on ...(day, month, date, year)...
Your contribution and participation in this gathering will be of great benefit to the participants. The Centre would like to thank you in advance and look forward to receiving your favourable reply soon.
Sincerely,