quoted-printable

Quoted printable (also called QP encoding) is an encoding system used primarily in electronic mail transmission to transfer texts encoded as ASCII (American Standard Code for Information Interchange) characters. It is a 7-bit ASCII transfer encoding that is used to minimize the number of bytes used to represent text in an e-mail message.
Quoted printable encoding is used to encode subsets of the US-ASCII character set, typically TOOLS characters that can not appear in standard headers, and for non-English/European text. It is derived from the earlier UUENCODE, with the objective being to reduce the amount of white space (blanks and tabs) in a transmission while still allowing all 128 ASCII characters, a range of national characters, and the CR/LF (carriage-return/line-feed) character pair. The quoted strings are defined as a sequence of octets encoded into printable US-ASCII characters.
To represent the octets in the printable ASCII format, quoted printable encoding divides octets into two categories — printable ASCII characters and all other octets. The encoding scheme translates all octets that do not correspond to printable ASCII characters into a maximum of three 7-bit ASCII characters.
Quoted printable is a useful way to deliver attachments, such as images and documents, with minimal deterioration of the data.The advantage of quoted printable over other encoding schemes such as UUENCODE is that the encoded text takes up less space, since octets are represented as a single character rather than six characters.