Abstract: A computer-implemented method for regulating delivery frequency of outbound communications. The method includes receiving message context data comprising one or more of a user identifier, a client identifier, a campaign identifier, a channel identifier, a label identifier, and a trigger identifier. A counter-field identifier is determined that encodes the channel identifier, label identifier, trigger identifier, campaign identifier, and a temporal-interval indicator. A counter field identified by the counter-field identifier is created. A value stored in the counter field is incremented through an atomic operation. The value is compared with a limit stored in a rule set. An allow signal is output when the value does not exceed the limit and a suppress signal is output when the value exceeds the limit. An engagement-counter record is updated to the in-memory database.