GoToList provides an easy way to send emails to many people at once. When you're viewing the records you'd like to email, click on the "Send Mail" icon bottom left and you're email client with open and the addresses will be filled in.
Unfortunately, by default Outlook manages this process differently from every other email client out there.
Good news is there's an easy fix. The bad news is you need to change an option within Outlook.
While in your Outlook client, go to Options, select Mail, and check the box that says "Commas can be used to separate multiple message recipients".
We wish Microsoft would just turn this on by default, but we're not throwing stones ...