[thereticent]

Is there anything wrong with the idea in the first blog comment? I would think sending the hashes to one or more webmail accounts in your own name would accomplish the feat of proof, and it would not require you to rely on other people to safeguard the data or give testimony.

[JoachimSchipper]

How do you prove the e-mail wasn't changed? At least gmail allows you to upload pretty much anything (which is useful when migrating mail), and may not be able/willing to turn over (old) logs.

[DennisP]

If they were simply unwilling, a subpoena would fix that.