I'm using Thunderbird as my email client to check a Gmail account.

I get a lot of emails from family who are located in different time zones. Now, my emails don't arrive out of order, but the timestamps are sometimes out of order so that when my email client sorts by date, it's not necessarily in the order sent. This is confusing when I check a day's worth of emails and I'm forced to read them in an order that's only lightly correlated with their "real" order.

Is this likely to be a problem with my computer, my email server, the senders' computers, or the senders' email servers? Between all of us and our computers we touch probably 6 or 7 different time zones around the world. I would think that ALL computers handling email would just handle UTC timestamps, until the very last computer (the client that displays the email in human-readable form) localizes it to the user's time zone. But it's not behaving this way and I'm wondering where I can start fixing this.