There is an option in the config to limit the amount of bandwidth used by the relay.
BandwidthRate N bytes|KBytes|MBytes|GBytes
In combination with accounting you can limit monthly or daily usage - has to be over 30kb/s to be usable by the network, so may not be feasible, but worth knowing.
BandwidthRate N bytes|KBytes|MBytes|GBytes
In combination with accounting you can limit monthly or daily usage - has to be over 30kb/s to be usable by the network, so may not be feasible, but worth knowing.