Conferences get cancelled for a variety of reasons. While it is acceptable to cancel a conference, it is not proper etiquette to neglect letting those who are planning to attend know about the change. Cancellation letters are the most effective means for spreading the word that the conference has been cancelled. The administrative staff who collects RSVP information should have the contact information for those who are planning to attend the conference, so ask for a list of the names and mailing addresses so you can send them a cancellation notice promptly.
Address the letter to each individual, if you can. If the conference is too large, you may not have time to address the letter to every individual on a personal basis. In this case, address the letter to a general audience. Write something such as "Dear Conference Attendees" or "To Whom it May Concern."
Write that you regret to inform the addressee that the conference has been cancelled. Write the name of the conference, including the date and time that was supposed to have taken place. The more clarification you provide, the better. Some people sign up to attend many conferences around the same time, so they will need to know the exact conference that is being cancelled. You can say "We regret to inform you that the conference 'Changing Minds in Business,' scheduled for May 4th at 2 p.m., has been cancelled."
Apologise for the inconvenience. Some people who RSVP'd may have had to make special arrangements and accommodations to be able to attend, and it may be inconvenient for the meeting to have been cancelled abruptly. Say, "We sincerely apologise for any inconvenience this change may cause you."
Inform letter recipients of the next step. If the conference is being rescheduled, say so. Give the time and date that the conference has been moved to, with instruction to RSVP for the new date. If the conference is not going to be rescheduled, it is important to let the readers know this. You might write "For now, this conference is not being rescheduled, but we will let you know if this changes."
Provide instructions for who people should contact with questions or concerns. Include the name, telephone number, fax number and e-mail of the appropriate contact.
Sign the letter and type your name beneath it. This lets recipients know that the cancellation letter really came from you, and is not a hoax.
You can include the words "Conference Cancellation Notice" at the top of your letter to make sure readers immediately see what the letter is regarding. You may also decide to print the notice on the outside of the mailing envelope. If the conference required attendees to pay an attendance fee, attach the refund policy to the back of your cancellation letter, and inform readers to follow the steps to get their money back.