Reticulum messages (LXMF, the format Sideband, MeshChatX, the iPhone apps and Nomad Network share) go directly to the recipient when they are reachable. When they are not, because their radio is off, their phone is out of range, or their laptop is shut, the sender's app hands the message to a propagation node instead. The node holds it and delivers it when the recipient next appears and asks for their messages.

Propagation nodes also exchange held messages with each other, so it does not matter whether the recipient uses ours or one somewhere else on the network. Ours syncs with other propagation nodes across the wider Reticulum network, so messages routed through it reach well beyond Scotland.

Everything the node holds is encrypted for the recipient. The node can see that a message exists and who it is for, and nothing else.

MeshChatX and Sideband pick a propagation node automatically from the ones they hear announcing, and ours announces every hour, so after connecting to ScotMesh you usually need to do nothing.

To choose it by hand, or to check:

• MeshChatX: in the messaging settings, set the propagation node to the address above.

• Sideband: Settings, then the propagation node section, and paste the address; there is also a button to use the last one heard.

• Retichat and Columba (iPhone): the propagation node is in the app's settings; paste the address.

Your app then also fetches from the node: it asks for waiting messages when it starts and at intervals after that. If a message you were expecting has not arrived, ask the app to sync with the propagation node; the option is usually next to the address.

Nomad Network: in ~/.nomadnetwork/config under [client], set propagation_node to the address, or pick it from the network view. Its conversations tab has a sync option.

Your own program: the LXMF (github.com/markqvist/LXMF) library takes a propagation node address in its router; the address above is the one to use for ScotMesh.

Messages are held until they are delivered, within the node's storage limits. It is a message store, not an archive: once a message has been collected it is removed, and very old undelivered messages are eventually dropped to make room. Treat it as a way to reach someone within days, not as somewhere to leave things for months.

A propagation node is one more service on a transport node: install lxmf and run lxmd with propagation enabled in its config. If you run one, tell us and we will point people at it; two are better than one.