A Definition

Email is now the world's most common method of communicating. An "email" means two things, viz:

  • The means of sending a message viz "by email"
  • The content of the message viz "the email"

However, these are two distinct things which are commonly confused with one another.

There are a number of things to be considered regarding each of these two meanings.

No Proof of Delivery

First is the question of "delivery". Was it delivered, and if so how does one prove that.

There are three main protocols viz:

  • SMTP or Simple Mail Transfer Protocol, although this can also be used "Securely"
  • POP or Post Office Protocol.
  • IMAP or Internet Mail Access Protocol

Neither of these protocols includes for "proof of delivery". SMTP simply sends a message on from one place to another. POP allows the downloading of a message from a server, and optionally to delete the message from the server from which it was downloaded.

So normally most systems use SMTP to send messages, thereby keeping a copy on the sending server, and POP to download [i.e. receive] messages.

The ONLY way that proof of delivery can be made is by the recipient formally acknowledging receipt to the sender. And this is accepted by the Courts. Prooving that you sent an email does NOT prove that it was delivered.

Alteration of Content

ALL email is sent simply as text. Thus anything other than simple text is sent using the MIME standard to convert it to use other characters as the internet uses only 7-bit ASCII - that is the codes 0 to 127. Hence anyone with a text editor can alter the content of an email. This includes attachments.

When an email is responded to using the classic "Reply" button, it is is normal practice to include within the response the whole of the message without the attachments. However the body of the received email can be edited - which can lead to mega confusion - and when emails are sent and replied to with multiple copies - the "true" version can become somewhat indistinct which can lead to major misunderstandings.

Attachment's are actually sent as part of the stream of text forming the email. These are separated by a set of characters called a boundary. The attachment can of course be edited. 

Acknowledgement of Receipt

Thus formal acknowledgement of receipt becomes an important, if not vital, part of the process. In effect it means that the content AND the attachments have been safely received, and that implies that they have NOT been altered and can be read by the recipient.

A guaranteed tamper proof mechanism is simply not possible. However, a formal, yet easy to use, system using EDI and HTML forms with server side processing is most likely to provide reasonable assurance.