| Value | Meaning |
|---|---|
| Default0 | Default transfer encoding. |
| _7bit1 | 7bit text transfer encoding. |
| _8bit2 | 8bit text transfer encoding. |
| Binary3 | Binary transfer encoding. |
| Base644 | Base64 transfer encoding. |
| Quotedprintable5 | Quoted-printable transfer encoding. |
| Uuencode6 | Uuencode transfer encoding. |
A Content-Transfer-Encoding enumeration.