The Welcome Letter is what walks you through the initial setup of your Comporium system. This is where you have the first change to enable/disable notifications, name devices, and other options. Most importantly, it's where you set your credentials for you system. The Welcome Email is only valid for 7 days after your purchase. If you need a new welcome email just let us know and we'll get one right out to you.
If you're having trouble locating your Welcome Letter, be sure to check your SPAM folder. The email will be from Comporium.