Question 1

The custodian deleted emails months ago. Can they be recovered?

Accepted Answer

Run the four facts: if a hold predated the deletion, yes: the Purges/Versions layers kept them, dated; if no hold and the recoverable window has passed, not from the mailbox: and the architecture paths (device caches, counterpart tenants, backups, journals) take over, frequently successfully. The answer is never "probably": it is an hour's tenant lookup, and the honest report states which case applies and why.

Question 2

Can a user or admin permanently destroy mail on a held mailbox?

Accepted Answer

Users, no: every user-level deletion route ends in a preserved layer while the hold stands, and the attempts are enumerable (Example 1). Admins can release holds and alter retention: actions that are themselves audit-logged and, mid-dispute, approximately confessional. The practical assurance: a hold placed early and left alone converts the mailbox into an append-only record: which is why the week-one hold is this block's recurring hero.

Question 3

How do we prove the other side received and read an email?

Accepted Answer

In layers of strength: transport trace (delivery to their tenant: strong, window-bound); their mailbox's collected copy (existence at collection); audit read-events where licensing and configuration recorded them (guide 57: genuine read evidence, not universal); and conduct corroboration (replies, forwards, actions consistent with knowledge). Read receipts are weak and refusable. The report stacks what exists and names each layer's weight: "delivered, present, and acted upon" usually suffices where "read at 14:32" is unavailable.

Question 4

What about the OST file on the laptop: is it worth collecting?

Accepted Answer

Frequently decisive: the OST is the mailbox as last synced: which means it can preserve what tenant-side deletion later removed, capture the pre-purge state of a mailbox whose hold came late, and survive the account's deletion entirely. Guides 41 and 48's imaging disciplines apply; the comparison of OST contra tenant is itself a deletion chronology. In leaver and spoliation matters, the device cache is standard scope, not an afterthought.

Question 5

Are auto-forwarding rules really that significant?

Accepted Answer

Repeatedly: a rule forwarding to a personal account is a continuous exfiltration channel with a creation date, an author context and (in audit) a paper trail: and its discovery reframes matters instantly ("what left, since when, and where did it go" becomes computable). The configuration export costs minutes; check it in every departure, leak and fraud matter before anything else is theorised.

Question 6

Our exhibit email is challenged as fabricated. What should we commission?

Accepted Answer

The Example 3 workup, from your side: full item with headers and properties from every layer of your mailbox; counterpart collection or requests at the other end; transport and authentication analysis; and layer-coherence review (does the item sit in the stores a genuine message of its date would occupy, including hold structures?). Genuine messages pass this convergently and fast; the report then carries CPR 35 weight the bare exhibit never could. Commission it before the hearing, not after the insinuation lands. cflab. u k · e-disc ove r y. u k ©2026 Computer Forensics Lab Ltd ·cflab.uk ·e-discovery.uk ·info@cflab.uk ·+44 (0)20 7164 6915 Page 15 of 17

Forensic Collection Of Exchange Online Mailboxes