Start with the account type
A managed Workspace account may have an administrator and organisation-controlled settings. A personal Gmail account is a different evidence environment. The email address and interface alone do not establish all applicable features, licence entitlements or preservation settings. Ask who controls the account and what authority exists to obtain its records.
Treat sources separately
Gmail exports, local mail copies and authorised organisational records each have a defined scope. Vault offers retention, hold, search and export functions for supported Workspace data when the necessary conditions are met. It is not a universal backup containing everything ever sent or deleted. A normal mailbox export should not be described as a Vault collection.
Document the route
Record the account, selected data, export creation time, settings, errors and supplied metadata. Preserve the original archive before processing. Labels and folders may be represented differently by different systems, so explain transformations in any comparison. When an expected message is absent, investigate scope and retention before concluding that it never existed. An initial assessment should identify available account, endpoint and correspondent sources without assuming access to the entire organisation.
Sources & further reading
Primary references support the technical explanation. They do not establish D3 validation of a particular method.