Sort email by oldest first
When working in an email list it is often useful to start at the oldest email first. You can do this by clicking on the email count and selecting 'Oldest'.
Select any email list and, where you have an accurate count (eg 1 - 50 of 500), hover on the count to see a drop down showing the options Newest and Oldest. This will sort the email in that list by date - newest first, or oldest first.
Where there is only a estimate (eg 1 -50 of many) it is an indication that GMail has not yet counted all your email in the chosen list and the sort option will be greyed out.