Re: What is Content-Transfer-Encoding: quoted-printable?
Sunday, November 21, 2004 06:52 AM
Read the RFC's. www.ima.org is a good site to look up mail-related RFC's.
Basically, Internet email was designed when only 7-bit ascii was completely "safe" from being damaged in transit, because transfer agents under basic SMTP (unlike ESMTP with certain extensions) are completely free to chop off the high-order 8th bit of characters they handle in transit.
So, as you have noticed, "quoted-printable" is a way of encoding 8-bit characters in 7-bit ascii, where for instance, the sigle linefeed character is encoded as "=20". Quoted-printable is intended for use when a message is nearly all 7-bit ascii except for a few extended (8bit) chars here and there.
For encoding lots of arbitrary characters and other data in message content, use "base64".