How do I send an email with an attachment using the Zimbra SOAP API?

First upload the attachment to obtain an `aid`. Then call the `SendMsg` command with the `attach` parameter referencing that `aid`. The request must include the sender (`<e>`), recipient, subject (`<su>`), and body (`<mp>`). Set `noSave` to 1 to avoid saving a copy in sent items. This process is explained in the Zimbra SOAP API Development Guide 3 - Email Operations, which extends the base API usage from the Zimbra SOAP API Development Guide.