Information Regarding Red Exclamation Mark in Emails

Hi all,
I was just testing email from 2 of my servers,
I noticed a red exclamation mark on one of my emails (Just beside the sender name). Can anyone explain what it is about. the screenshot is given in the following link.

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It just denotes the presence of one of these MIME headers in the message header (usually X-Priority):

X-Priority: 1
X-MSMail-Priority: High
Importance: High

It means the sender marked the message as “High priority”. It is not authoritative in any way, and only signal the intent of the sender.