What if…

…your email client had the following bits of functionality:

Based on hours you set in your calendar client, emails received outside of work hours are buffered into a "Look at tomorrow" mailbox that you do not see unless you go looking and the sender receives a note that says "This message was received outside normal working hours. If this is an emergency that requires immediate-ish attention click on the link below. Otherwise, i will read it when I'm next at my work desk. For true emergencies, call or text me."

An algorithm in your client assesses the number of unread messages in your inbox and advises your correspondents where there message is in the queue of recent messages (you can set how far back it will count).

When you are on vacation your client's vacation message has some extra options: it can be set to delete incoming emails and send a message back to the sender saying "I am on holiday at the moment and not back until XXX. If this message will still be relevant then, please resend at that time. If you need immediate help, you might try getting in touch with someone else."

An algorithm watches the pattern of your email response behavior PLUS the state of your calendar, to-do list, and a schedule of deadlines, projects, etc. Incoming mail is scanned for sender and content and evaluated for relative urgency and how long it would take to deal with. The sender receives an estimate of how long it is likely to take you to reply. They are given an option of accepting this place in your work queue or of recalling the message.

An algorithm scans incoming email and based on how you have replied to previous emails it suggests a disposition and response. Some are completely canned and require only a confirmation. Others are available for editing.