There are four ways to upload documents into DOKKA. Number three is via email. Every company has a unique email address. Email invoices to that address and they are automatically uploaded into DOKKA. You'll see it appear in your workspace.
The default address is a string of numbers (accountants like numbers). You can change it to something more meaningful. Here's how:
Click on the Setting cogwheel.
Enter your choice of address in the email field and click Save.