Hello,
Can you verify what method you used to send the email? Also, in "WHM >> Exim Configuration Manager", under the "Mail" tab, let us know if any of the following options are enabled:
EXPERIMENTAL: Rewrite From: header to match actual sender
Set SMTP Sender: headers
Query Apache server status to determine the sender of email sent from processes running as nobody
Trust X-PHP-Script headers to determine the sender of email sent from processes running as nobody
Thank you.