Every job opens with the audience set down on paper. The file is deduplicated against anything previously supplied to you. Nothing is enriched from a source that cannot be named.
Correction
Updating what has changed, wherever a current value can be established.
Decay review
Identifying the records that have stopped being current, and how many of them there are.
Monitoring
Watching for the configuration changes that quietly stop mail arriving.
A requirement written in a paragraph is enough to begin.