Winlink, or formally, Winlink Global Radio Email (registered US Service Mark), also known as the Winlink 2000 Network, is a worldwide radio messaging system that uses amateur-band radio frequencies and government frequencies to provide radio interconnection services that include email with attachments, position reporting, weather bulletins, emergency and relief communications, and message relay. The system is built and administered by volunteers and is financially supported by the Amateur Radio Safety Foundation. Network Winlink networking started by providing interconnection services for amateur radio (also known as ham radio). It is well known for its central role in emergency and contingency communications worldwide. The system used to employ multiple central message servers around the world for redundancy, but in 2017–2018 upgraded to Amazon Web Services that provides a geographically-redundant cluster of virtual servers with dynamic load balancers and global content-distribution. Gateway stations have operated on sub-bands of HF since 2013 as the Winlink Hybrid Network, offering message forwarding and delivery through a mesh-like smart network whenever Internet connections are damaged or inoperable. During the late 1990s and late 2000s, it increasingly became what is now the standard network system for amateur radio email worldwide. Additionally, in response to the need for better disaster response communications in the mid to later part of the 2000s, the network was expanded to provide separate parallel radio email networking systems for MARS, UK Cadet, Austrian Red Cross, the US Department of Homeland Security SHARES HF Program, and other groups. Amateur radio HF e-mail Generally, e-mail communications over amateur radio in the 21st century is now considered normal and commonplace. E-mail via high frequency (HF) can be used nearly everywhere on the planet, and is made possible by connecting an HF single sideband (SSB) transceiver system to a computer, modem interface, and appropriate software. The HF modem technologies include PACTOR, Winmor(deprecated), ARDOP, Vara HF, and Automatic Link Establishment (ALE). VHF/UHF protocols include AX.25 Packet and Vara FM. Amateur radio HF e-mail guidelines Amateur radio users in each country follow the appropriate regulatory guidelines for their license. Some countries may limit or regulate types of amateur messaging (such as e-mail) by content, origination location, end destination, or license class of the operator. Origination of third party messages (messages sent on behalf of, or sent to, an end destination who is not an amateur operator) may also be regulated in some countries; those that limit such third party messages