| Content-Type: multipart/mixed; boundary="outer-boundary" | |
| Outer preamble | |
| --outer-boundary | |
| Content-Type: text/plain | |
| Foo | |
| --outer-boundary | |
| Content-Type: multipart/alternative; boundary="inner-boundary" | |
| AAA | |
| --inner-boundary | |
| --inner-boundary-- | |
| --outer-boundary-- | |
| Outer epilouge |