Yep, it sure is. It works great for me. I use Outlook to access my work email from home and Outlook Express is set up for my ISP, but I have that in Pop Peeper too so I very seldom use Outlook Express. The only quirks I have run across are some emails with lots of graphics don't show quite right and those I go to the email client to see. I don't respond much to email from Pop Peeper even though it is capable of doing that. I had rather go to actual email program when I want to respond.