nym/documentation/docs/src/sdk/rust/examples/surbs.md

Anonymous Replies with SURBs (Single Use Reply Blocks)

Both functions used to send messages through the mixnet (send_message and send_plain_message) send a pre-determined number of SURBs along with their messages by default.

The number of SURBs is set here.

{{#include ../../../../../../sdk/rust/nym-sdk/src/mixnet/client.rs:33}}

You can read more about how SURBs function under the hood here.

In order to reply to an incoming message using SURBs, you can construct a recipient from the sender_tag sent along with the message you wish to reply to:

{{#include ../../../../../../sdk/rust/nym-sdk/examples/surb-reply.rs}}