A very limited email server, e.g. using postfix

I understand the negatives about running your own email server, but I have requirements that are extremely limited, but also need a bit more flexibility than I expect to find in a 3rd party service.

I would like to be able to receive documents through emails to a limited set of target email addresses, from a limited set of registered senders. The basic goal is to make it easier for naive users to post documents to an incoming queue by letting them do it through familiar email tools and attachments.

For protection the target email addresses would be randomized, hard-to-guess, and highly disposable. If it starts to get junk we’d throw away the address and make a new one. In addition, they would only be allowed to receive emails from known senders. All other senders’ emails will be immediately discarded.

I am expecting it will hard to find a service focused on such a use case. Or at least I expect it would be pricey and or inconvenient to automate. But maybe I’m wrong. So any service recommendations would be wonderful.

So here are my distilled questions:

• Is there a service that can effectively deal with server-managed disposable inboxes?

• Is it safe and a valid use case to set up a very tight postfix installation that provides this highly restricted access?

• Can it safely omit a spam filter, if it discards unknown senders and no actual people-users are receiving these emails?

I’m far from an uber-administrator. So I’d greatly appreciate being pointed in the right direction.

Thanks in advance!