In order to get most out of Propeller, you currently need to have your company's email hosted through Google Apps / Gmail.
If you're on another email system and want to migrate to Gmail, there are some good resources to help you along the way.
If you're on a hosted mail service like Office 365 of GoDaddy, there's a good chance you can use Google's Data Migration Service.
If you're on your own Exchange server, join the rest of us in the 2010's by trying Google's G Suite Migration for Microsoft Exchange (GSMME).
For other DIY options, you can check out the full range of migration options here.
And if all this sounds like too much to bear, get some help! There are a number of Google Apps resellers who will migrate your email for you at no additional charge. Here's one directory you can try.
One important thing to note: just because you migrate your email to Google Apps does not mean you have to abandon Word, Excel, and PowerPoint.