"Heck, who here hasn't been reminded by gmail that you said you 'attached' something, but you don't have attachments?" Is this something that requires Google s

"Heck, who here hasn't been reminded by gmail that you said you 'attached' something, but you don't have attachments?" Is this something that requires Google servers to inspect your mail? Pretty much every email client I have ever used does this even if I have no Internet connection. It is really a matter of matching a regular expression and checking if there are any attachments to a message being composed.