josh wrote:Adding the message to the message body would pose some development (and performance) challenge to us because we'd have to evaluate multi-part MIME messages in a special way to make sure that we're changing the right part
I've had a problem with another disposable mail service which adds a note to the body (I think it was Kasmail). Once I got an email which main body (not attachment!) was base64 encoded. But the note was added anyway. Luckily I know about rfc2045 and I am able to use my mail client, so I was able to recover the message.
Another point: Even if the mail is not base64 (or quoted-printable), could one really assume that any possible charset used by anyone will be downwards compatible to us-ascii?
Does every mail really require a text/* part, or can I send a "attachment" only message?
Modifying the body seems really dangerous to me. It will surely work just fine for 99.9% of all events, but it may fail some day.