Rules for ex-Presidents:
1) not allowed to drive in open roads
2) constant security updates so they can answer questions by the press or advise current President
3) must create a Presidential library
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4) Secret service can monitor the ex-Prsidents communications and correspondence to keep the President safe
5) have Sectet Service be with you 24/7/365
But the ex-President can opt out of Secret Service protection. I expect Trump to take that option to avoid the monitoring of communications and hire his own security