It’s pretty simple really.
“Does not fall within my jurisdiction” is a weasel excuse guys like Mueller use to wiggle off the hook. He had probably been saying that his whole life.
When his thoughts clouded that was his default mode.
He was playing. He is a weasel.
The emails were not within the mandate because Justice knew from the beginning that they were hacked by the Chinese, not the Russians. They also knew that the DNC emails were not hacked by anyone but were stolen from the servers at DNC headquarters. All of the foundational issues creating the SP were planted by Justice and deserved no scrutiny.
The purpose of the SP probe was to keep the president off balance and create sympathy for impeachment. By the time Barr became involved the wheel spinning had been going on for 2 years +. He (Barr) discovered there was no there there and demanded a final report within 30 days. Hence, the Mueller report.
It is a treatise of lies, distortions, distractions, and other tomfollery promulgated in lieu of any legal justification for the so-called investigation.
The president has put this monkeyshine show to bed by giving its instigators enough rope to hang themselves. The man is fearless.