Quoted-printable
A MIME transfer encoding for mostly readable text that leaves plain ASCII alone and writes other bytes as = plus two hex digits, such as =C3=A9 for é in UTF-8.
What it means
RFC 2045 designed quoted-printable so that encoded text stays largely legible. Bytes outside printable ASCII, and the = sign itself, are written as =XX in hexadecimal; lines are kept to 76 characters, and a line ending in = is a soft line break that joins the next line. It suits HTML and text in Latin-script languages.
Seeing =3D, =20 or stray = signs at line ends in a received message means a program displayed the encoded text without decoding it, usually because the Content-Transfer-Encoding header was wrong or missing. Because it keeps lines short, quoted-printable also keeps HTML within the line length limit.
Example
Votre facture d=C3=A9taill=C3=A9e est pr=C3=AAte.Related terms
Sources
What this definition rests on. The wording is ours; the facts are theirs.
All 432 terms in the glossaryThe wiki: blocklists and bounce codes