The sassanids would never accept the permanent loss of mesopotamia.
only if you can prevent the loss of the heartland in the derbent aral sea region which was a major source of sassanian power and in fact Persian power. After all ctesephon was sacked many times but the perisans always won it back because till the arabs the Persian heartland had been since Parthian times really untouchable by outsiders. After all whichever dynasty seized the heartland successfully would go on to become the ruling dynasty. As long as it was held the Persians had a chance to bounce back. The romans came close but even they failed.
The sassanids would never accept the permanent loss of mesopotamia.
They're not suicidal, they may not accept it but if its clear to them they will lose any wars to reclaim it they will almost certainly atleast wait for a time of weakness for the Rashiduins. Also with time they may come to appreciate losing their border with the Byzantines if the Rashiduins prove to be less of a threat.