If I receive a message like this, whether by SMTP, FTP, HTTP, HTTPS, TCP or NNTP, I have enough information to proceed and process it.
<envelope>
<header>
<from>Inventory.Orders@Dell.com</from>
<to>Accounting.Invoices@Contoso.com</to>
<subject>Invoice</subject>
</header>
<body>
<invoice>
<!-- invoice here -->
</invoice>
</body>
</envelope>
Let the protocols do their job and let's keep messaging simple.
For god's sake, stop the madness and let's start exchanging messages now!