Reason #1: Professionalism
Which of these tells the recipient that it’s coming from a business?
I hope you picked the second option because you can quickly tell that it’s coming from someone at Primate Project and not some random person with a Hotmail account. The first one looks like it might be from a spammer, and there’s a good chance that it will automatically end up in the recipient’s spam folder.
Plus, that second email address is a lot easier for me to remember. When I need to write an email to Janet, I just need to remember she works for the Primate Project. Her email address is easy to remember because it’s her name and her business.