Thank you for the suggestion.
My clients have a lot of hourly employees that they need to communicate with but for privacy reasons, they don't necessarily want to use a corporate or private email address.
For example, a manager may want to use his private phone to send an email to a group of employees. Any replies would be routed to his secretary at the office --- with all addresses remaining semi-anonymous. My software will handle all this with the help of your service.
I currently have several hundred clients with a total of over 20,000 employees.
In other words, this all strictly opt in --- no marketing.
There is an open source product called IMAP API which is available under 2 licenses depending on your needs: AGPL & MIT. It recently had its own Show HN [2].
I need API access to obtain sender and destination address of mailbox item and then decide how to dispense with it, either delete, retrieve or forward to a different destination. "Destination" may involve dozens of addresses. Reply address may be changed.
To minimize storage and costs, any item over 24 hours old can be deleted.