Regrets Only Reply If Cannot Attend

Dear Dr. Dave and Dr. Dee,

If the invitation states Regrets Only, do I need to respond if I can attend or only if I cannot attend? Also, what do I say as to why I cannot go?

Signed,

Not Sure

Dear Not Sure,

Regrets Only need a response if you will not be able to attend. In other words, if you do not respond, then they plan to see you there.

You do not have to have a reason for not being able to attend. You can simply write that you regret that you will be unable to attend. If you wish to give a more elaborate response, you can write that you are sorry that you are unable to attend the event, but you have another engagement, or will be out of town, or have a conflict with that date.