Systems for prosecuting Internet messaging campaigns. Two or more data sources are determined where at least one of the data sources comprise demographic attributes corresponding to shared IDs such as recipient IDs. A first join operation is performed over matching instances of the shared IDs in the two or more data sources. The first join operation results in a personalization table comprising rows having at least recipient IDs, respective external addresses, and at least one of the demographic attributes. The personalization table is transformed into a key-value data structure that is published to a caching subsystem. The caching subsystem is used to select a first set of recipients determined without performing a second join operation. Personalized messages to at least some of the first and second set of recipients are formed using the message template and the key-value data structures.