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What Does the [Ext] Before a Subject Line in Outlook Email Really Mean?


Our Cybersecurity team instituted a policy that puts [Ext] before the subject line of external email messages to let you know the email was not from an internal source.

But sometimes you get legit emails from institutions (St. Jude, ROH, Le Bonheur), professional associations (AMA, ADA), higher ed associations (EDUCAUSE, ACGME), or vendors (Roche, Fisher Scientific) that are considered external sources.

Even our ITS newsletter has the [Ext] prefix because it is sent through MailChimp.

The [Ext] is a simple reminder, “Hey, this email may not have come from an internal UTHSC source, so use caution when opening it.”

Have a question about a suspicious email? Either forward it to abuse@uthsc.edu or contact our Cybersecurity Office at itsecurity@uthsc.edu.