Gmail puts the newer emails first as follows:
- anita@openmailbox.com | Dogs issue | 19:40
- pepito@hotmail.com | Important facts from Jupiter | 14:03
- juanito@gmail.com | You coming? | 09:25
Everything else (already seen email)
- tsstss@openmailbox.com | Dinosaurs still exists! | 17:13
- jaja@hotmail.com | Yep or Nope | 14:08
- blabla@gmail.com | Whatever? | 09:27
I think it is better to start reading the oldest non-seen emails:
- juanito@gmail.com | You coming? | 09:25
- pepito@hotmail.com | Important facts from Jupiter | 14:03
- anita@openmailbox.com | Dogs issue | 19:40
Everything else (already seen email, same order: first the newer email)
- tsstss@openmailbox.com | Dinosaurs still exists! | 17:13
- jaja@hotmail.com | Yep or Nope | 14:08
- blabla@gmail.com | Whatever? | 09:27
Is it possible? How?
UPDATE (from comments)
Gmail does not have an option for that. However, maybe there are some Greasemonkey scripts able to do that. Or some Chrome or Firefox extension.
Best Answer
It's not possible to change the sort order in Gmail but some other tools like IMAP and POP desktop clients have that feature.
The built-alternative to changing the sort order, is to use Gmail search (see [1]). It includes search constraints. Also, could be used the search operators "before", "after", "newer" and "older".
From [2]
References
[1] Search in Gmail - Gmail help
[2] Advanced search - Gmail help