I just received two emails from a friend. Both were sent within one minute of the other. An important note: both were sent from an iPad's "Photo" app and so both emails contain one photo each.
The first email was sent at 11:27 am, according to the Conversation view (when viewing the email directly), which I believe to be the correct timestamp. However, in the List view (where you can see a list of multiple emails, such as in the Inbox), the time for this email is 11:31 am.
For the second email, it was sent at 11:28 am in the Conversation view, but the List view gives it as 11:30 am.
So not only are the timestamps incorrect, but the order of the emails are backwards. There is only one email in both email conversations.
I've only seen this happen perhaps once before, in 2004 when I first migrated to Gmail. At the time, I imported all my non-Gmail email to Gmail by using POP3, and so the List timestamp was the time that I imported the email, while the Conversation timestamp was the actual timestamp of the email.
Why is the timestamp incorrect in these two recent emails? I'm guessing it has something to do with how an iPad sends out emails, and the second one must've been sent out first, perhaps because the image in it was uploaded more quickly?