You're looking at Contact record details and stumble upon a suspicious "View Mailings" listing for that person. Why would test mailings be in their history?
This image displays an example listing that includes the [TEST] mailings:
When testing emails from your account, the system will merge in a random contact from the segment assigned to the email campaign. It is common to see that the email in the To field and in the footer are not your email address. This occurs to accommodate for any merged information validation being used in the email campaign. What also happens is that the test mailing, though not actually received by that person, is added to their received mailing history.
If you have questions about tests or other reporting, feel free to contact our Support team. We're here for you!