nDerek reviews the other e‑mails he has received on Tuesday and decides
that 15 of Monday’s messages must receive replies on Tuesday, giving them a set point of 24
hours. That means he has the feeling they have
aged to the point at which the senders must receive replies or there’ll
be problems.
nThat
leaves 42 e‑mails from Monday and Tuesday in his in-box at the end
of the day on Tuesday.