This blog post is 5 years old and may be out of date.
Mullvad partnerships page has been updated - Mozilla
Mozilla has partnered with Mullvad in order to utilize our global network of VPN servers for its own VPN application.
Mozilla VPN: https://vpn.mozilla.org/
Mullvads list of Partnerships and Resellers has been updated: https://mullvad.net/help/partnerships-and-resellers/