Eo meaning executive order. I dont think a president has cared to try an eo for the usps, but anything is possible with him.

He could possibly eliminate the monopoly the usps has on the mailbox and the monopoly on first class mail.

In reality nobody (the majority) don't need mail 6 out of 7 days. Not even 5... Or 4.. Informed delivery is telling people "i dont need to go to the mailbox today." so delivery frequency may be looked at again.