If you are using Outlook and you are connecting to Exchange Online, you might see (depending on what your IT administrator has set) a big "External" label to the left of each From field on each email that has an external sender. This can be quite distracting, expecially if 95% of all your emails are coming from external senders.

You can remove that "External" label, by replacing the "From" column with a custom "From" field. Here is how to do it:

In Outlook, go to View > View Settings

Click on Columns...

Choose New Column...

Name: FromNoTag
Type: Formula
Formula: [From]

Move the new FromNoTag field between From and Subject

Remove the original From field

Click OK twice

This is it. The "External" label has now disappeared.