That's probably fine for doing your own thing but if you let your users generate email or you screw up and send something that's flagged to hell the established

That's probably fine for doing your own thing but if you let your users generate email or you screw up and send something that's flagged to hell the established relationships you don't have with the companies that provide spam filtering and/or email is going to hurt. If you're just sending out occasional newsletters or whatever the time to resolve that probably wouldn't hurt but if you're sending critical email on a frequent basis (like password resets) any delay could have a big impact.