Assembled once, checked twice.

Who to leave out is settled at the same moment as who to include. Where two sources disagree, the conflict is recorded rather than resolved silently. Format is tested on a sample before the full run is delivered.

Specification drafting

Writing down the field list, definitions and rules, so the same build can be repeated later.

Seed insertion

Placing known addresses in the file so you can see for yourself what was sent and when.

Rejection reasons

Every discarded row carries the rule that discarded it, in plain words.

A specification you can hand to someone else is the aim.