How to make the Username column in the GridView an email hyperlink and to be clickable?

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C#

I developed a web-based training matrix that shows the training record for each employee in each division in my department in the company. The matrix will show many columns such as the employee name, username, job title... etc. what I want now is to make the username for each employee to be clickable which means when the admin clicks on it, the outlook will be opened with his email and the admin will be able to send him a message. In my company, this is possible because each employee email is mainly as: username@companyName.com so how to do that?

By the way, the username of the employee will be retrieved from the database using a storedprocedure, so how I will be able to convert the username to an email and to be clickable at the same time using the Code-Behind?

The user column is the 4th column in the GridView