Mass Mail Features Request

The ‘Send as mass mail’ feature is very useful with the use of variables to personalise each email, but I would like to be able to schedule a start date and time and then send each individual email at a specified interval.

For example, I want to send a few hundred individual emails to a list of recipients, starting at 01:00 next Sunday, each one to be sent at a 90 second interval.

This is essential to avoid breaching send rate limits for one of my mail providers that will (silently) block in excess of 50 external emails per hour and prevent any further outgoing emails until I raise a support call to delete the backlog. Unfortunately, changing providers is not an option for various reasons.