RPost’s Registered Email service is used to provide a high standard of evidence in civil and criminal litigation. The service can prove to a court that a particular message was delivered and often even that it was read. (See yesterday’s bulletin for more.)

The techniques used to discover evidence that the message has been “read” are increasingly unreliable. Return receipts are sometimes disabled or made optional by mail clients or filtered by mail servers. An alternative technique uses “Web bugs” — remotely loaded invisible images in HTML message bodies — but these are sometimes thwarted by mail clients or boundary security devices.

Also, “delivery” in this context means successful SMTP delivery to the server responding as the mail exchanger (MX) for the recipient’s domain. This may not actually be the recipient’s mail server, nor even be run by the recipient’s organization. For example, the receiving MX could be:

* A hosted spam filtering service, such as Microsoft’s Exchange Hosted Services (née FrontBridge)
* A secondary MX, because the usual, primary server is down for maintenance

However, under section 15 of the Uniform Electronic Transactions Act, this distinction of “MX” vs. “mail server” is immaterial. As long as the recipient organization’s domain management has specified this MX for its domain, U.S. law deems receipt by the MX as being equivalent to receipt by the organization. It seems that “the spam filter ate your mail” is no defense.