Why does email from an iPhone have the wrong time zone in the Date field? Whenever my daughter sends me email from her iPhone, the email arrives with the wrong timezone in the headers. However, the timezone seems to be set correctly on her phone.

Her correct timezone is Eastern Daylight Time (EDT). However, look at the headers on the email I received (sanitized to remove identifying information):

Received: from my.example.com (localhost [127.0.0.1])
        by my.example.com (Postfix) with ESMTP id 70DDBF60347
        for &lt;myname@localhost&gt;; Thu, 14 Jul 2016 11:19:59 -0400 (EDT)
Envelope-to: myname@example.com
Delivery-date: Thu, 14 Jul 2016 11:15:44 -0400
Received: from another.example.com [11.22.33.44]
        by my.example.com with IMAP (fetchmail-6.3.26)
        for &lt;myname@localhost&gt; (single-drop); Thu, 14 Jul 2016 11:19:59 -0400 (EDT)
Received: from njbrspamp10.vtext.com ([69.78.129.155]:23060)
        by another.example.com with esmtps (TLSv1:ECDHE-RSA-AES256-SHA:256)
        (Exim 4.87)
        (envelope-from &lt;6175551212@vzwpix.com&gt;)
        id 1bNiMZ-0008Nw-LM
        for myname@example.com; Thu, 14 Jul 2016 11:15:44 -0400
Received: from 5.sub-69-78-32.myvzw.com (HELO m04.vzwpix.com) ([69.78.32.5])
  by njbrspamp10.vtext.com with SMTP; 14 Jul 2016 15:15:42 +0000
From: 6175551212@vzwpix.com
To: myname@example.com
Subject:
Date: Thu, 14 Jul 2016 15:15:42 +0000


As you can see, the final "Received" line has a timezone offset of +0000 (GMT), whereas all the others have offsets of -0400 (EDT). As a result, the "Date" line in the email (used by my email client) has a +0000 timezone offset instead of -0400, which is confusing because both sender and recipient are in the Eastern USA (-0400).

Is this a problem at Verizon (myvzw.com), on my daughter's phone, or somewhere else, and how can it be fixed?

Thank you very much.
The problem, I think, is with your mail client. The times in the headers are consistent, that is, the chronological sequence is correct. The issue is that your mail client is not translating the time given in the header into local time for display. This means that an email to you from, say, New Zealand would be shown in your mail client with a time that hasn't happened yet for you locally.

Verizon's cellphone equipment (e.g., ENodeB) is almost certainly set for UTC (alias GMT). That greatly simplifies their data aggregation issues.