Content-Type: multipart/mixed; boundary="0123456789abcdefghijklmnopqrstuvwxyzABCDEFLMNOPRSTUVWXYZ'()+_,-./:=?  "

multipart

--0123456789abcdefghijklmnopqrstuvwxyzABCDEFLMNOPRSTUVWXYZ'()+_,-./:=?  
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Text body
--0123456789abcdefghijklmnopqrstuvwxyzABCDEFLMNOPRSTUVWXYZ'()+_,-./:=? 
The above line is similar to the boundary but miss a final space, so it
should be part of the body.

--0123456789abcdefghijklmnopqrstuvwxyzABCDEFLMNOPRSTUVWXYZ'()+_,-./:=?  --
epilogue