Ages ago an add-on called MailTweak has a "tweak" called Defer, whichoffered this amazingly useful funcitonality..
[i]Defer
Defers messages until a later time.
This feature can be used on messages you have received. Deferred messages disappear from your Inbox. At the specified time the messages reappear in your Inbox, marked unread and optionally tagged with a tag that you specify.
The feature can also be used on messages that you send, so that they are sent at the specified time.[/i]
Like many, I sometimes browse or write email but see some that I want to hide away until office hours, or send replies that I would only like to go out at a specific time and day.
Any clues of any add-ons that can help with that?