how do i sort email messages by time received?

i get many emails per day and keep up with them hourly. I am noticing,
however, that by the time i get to late afternoon (and have continually kept
up with incoming mail) that some new mail is sorted by "time received"
earlier in the day. For example: at 12:00 i have read every single email and
have nothing in my in box that is marked as unread. But incoming mail is
sorted by "time received" hours earlier when i click send/receive.... 9:00 AM
for one example.

If mail sorts by time received (and there are no messages on my mail server
from earlier in the day), how does it get sorted by (9:00 AM when it is
actually received by my mail server at 1:05 AM (showing time received as 9:05
AM) and then shows up in OUTLOOK as being received at 9:00 and placed in the
descending order before all the other email i have already read. does this
make sense?