[boxit-server] we used heirloom-mailx 12.5-2+deb7u1
Since we used heirloom-mailx 12.5-2+deb7u1 back in the day we had no issues with sending attachments. With s-nail or mailutils we have some issues with sending proper emails via boxit.
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information