Despite the fact that student emails are not available for communication, students can still collaborate and share documents with just a few workaround steps.
Sharing a collaborative document is as easy as grabbing the Share link for the document, posting it on your website or in a Class Notebook and allowing students to work together on the document. If you are a Class Notebook user, consider assigning students to a small group to help manage the workflow and overcrowding of a document. Permissions can be granted to groups in Class Notebook from the management screen.
If you have students who have created a document in Sway, Word, PowerPoint, or Excel, they can share their document link with you directly from their Office365 account. If students need to share with one another, collect their shareable links in a Form, then the Form becomes a place for students to grab their group work and share their projects with one another.

These are just a couple of ways you can make collaboration a reality using Office 365 digital platforms. For more ideas, ask your TOSA!