Each transaction submitted to the MobileCoin network must pay a fee to the MobileCoin Foundation. The purpose of this fee is to prevent unlimited submission of transactions, which otherwise could be easily abused to degrade users’ experience. The minimum fee per transaction is 0.0004 MOB, and is always distributed to the following address (written in hexadecimal format):
public view key:\ 5222a1e9ae32d21c23114a5ce6bb39e0cb56aea350d4619d43b1207061b10346\ public spend key:\ 26b507c63124a2f5e940b4fb89e4b2bb0a2078ed0c8e551ad59268b9646ec241
MobileCoin launched with a hard-coded minimum fee of 0.01 MOB. When this constant was set, the value of MobileCoin was assumed to be slightly below 1 USD per coin, resulting in a per-transaction fee of under 0.01 USD (1c). This fee was too high to reasonably support the cannonical use-case—purchasing a cup of coffee—and we lowered the fee to $0.04 to bring it back in line with that use-case.
There is currently a proposal for the minimum fee to be configurable in the next version of MobileCoin’s protocol. Changing the fee configuration would require a coordinated restart of all validator nodes in the network.