Often times users will want to directly send files to one another via Mattermost. This can be accomplished at any time by selecting the paper-clip on the far right side of the "Write a message..." box, or by dragging and dropping a file into the direct message. Attached files will display as a preview beneath the message box. Remember to hit enter to send the message and attachment to your teammate!

[Please note] You can only upload 5 attachments at a time. After the first 5, just send a second message with the next group. Rinse, repeat.