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A question mark in place of a profile picture: This means that the sender has failed the authentication checks that make sure a message is sent from a legitimate person.
Banner messages, first time senders: If you are the only recipient, you will see, “You don’t often get email from…” If there are multiple recipients, you will see, “Some people who received this message don’t often get email from…”
Banner message, sender’s name is similar to but not the same as a previous sender: You will see, "This sender appears to be similar to someone who previously sent you an email but may not be that person."
Banner message, possible domain impersonation: When you receive a message from a domain (name of a website) that is similar to http://uconn.edu, you will see, “This sender might be impersonating a domain that's associated with your organization."
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