Custodian

Why collection is organised this way

Because that is how the material is actually held. There is no single place a company’s email lives as a coherent body; there are mailboxes, each belonging to a person, and the question of what is responsive is answered person by person.

Identifying custodians is therefore an early and consequential decision. Too few and the production is incomplete, which is the kind of gap the other side finds by noticing that a message in your production was sent to someone whose mailbox you never collected. Too many and the cost multiplies for no benefit.

Custodian as a metadata field

The word also names a field. Every production protocol asks for a Custodian value in the load file, recording whose collection each document came from.

This matters more than it looks. The same email exists in the sender’s mailbox and every recipient’s. Deduplication removes the copies, but the record of who held it has to survive — a message found in three custodians’ mailboxes tells you something a single deduplicated copy does not. Most protocols handle this with an “all custodians” field alongside the primary one.

The self-collection question

The cheapest collection is asking the custodian to gather their own responsive email. It is also the one most open to challenge, because the person with the most interest in the outcome decided what was responsive.

This is routine and generally accepted in small matters with cooperative custodians. It becomes a liability when the custodian is adverse, when spoliation is plausible, or when the case is large enough that the collection method will itself be litigated. The distinction is not really about firm size; it is about whether anyone is likely to contest how the set was assembled. See chain of custody.

Departed employees

The recurring practical problem. Mailboxes get deleted on offboarding, often automatically, and often before anyone thought about a litigation hold. If a former employee is a likely custodian, that is a question to ask on day one rather than during a motion.