Sorry to keep you waiting. / Sorry to have kept you waiting. [1] (We are) sorry to keep you waiting. [2] (We are) sorry to have kept you waiting. Are these two sentences correct and natural to use in business email? I searched online and found someone suggested that [1] uses in the situation people are still waiting for you to do something, and [2] is used when people have been waited for a long time, but no longer waiting. Is it correct? Normally, we use the sentences to our clients or counterparts in business, when we took long providing them some information, including quotation, delivery schedule, analysis report, or any other information they are asking for. It can be the situations that (A) we took long but finally got the information they want, being able to provide them, or (B) we still need some more time, so we can only give some progress update. In these cases, what kind of expression would you suggest to use? Thank you so much for your help!