4 of the 5 Office 365 Preferred Networking Partners are very large, long-time Microsoft partners (Citrix, Zscaler, Silver Peak and NTT). The fifth partner, NetFoundry, is a NaaS (Network-as-a-Service), Zero Trust networking startup.
According to Microsoft all 5 of the partners "have met Microsoft’s testing requirements" and "support a high-quality end user experience." Microsoft also stated that Cisco, Oracle and Riverbed are in the midst of trying to get qualified.
NetFoundry's O365 networking optimisation solution states that it is the only one of the 5 Preferred Partners to both enable the lowest latency Office 365 networking (direct Internet without trombone through third party cloud infrastructure), and not require a specific WAN solution, instead functioning as software-only NaaS, on top of any WAN. The same NetFoundry Platform used for O365 optimization also enables Zero Trust, private Azure connectivity, and has both NaaS and Developer Platform options. More details on the 5 selected Office 365 networking partners are on the Microsoft website here.
Galeal Zino, CEO of NetFoundry, stated "We are excited to be the first Zero Trust, NaaS provider to be a certified partner in the Microsoft Network Partner Program for Office 365. We are 'the easy button' for optimized O365 because our solution enables businesses to optimize O365, without implementing an SD-WAN solution or deploying hardware, while securing business sites with our Zero Trust solution, and without needing to send the data through third-party infrastructure."