Create a Post for a Source or Topic via email in the following way.
Within the Reader dashboard view, click on [Internal Sources] button on the left sidebar. Then, click on the [Edit] button next to the Source in which you would like to add content.
The dialog box shows you a unique email address. Sending an email to that email address adds that content as a Post to the specific Source or Topic.
You can change the email address by clicking on the [pencil] icon by the address, replacing the existing name and clicking [Update].
You could give this email to your employees without admin access, so they can add relevant content to Sources or Topics.