4.4 rfc2047

RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how non-ASCII text in headers are to be encoded. This is actually rather complicated, so a number of variables are necessary to tweak what this library does.

The following variables are tweakable:

rfc2047-default-charset

Characters in this charset should not be decoded by this library. This defaults to iso-8859-1.

rfc2047-header-encoding-alist

This is an alist of header / encoding-type pairs. Its main purpose is to prevent encoding of certain headers.

The keys can either be header regexps, or t.

The values can be either nil, in which case the header(s) in question won't be encoded, or mime, which means that they will be encoded.

rfc2047-charset-encoding-alist

RFC2047 specifies two forms of encoding---Q (a Quoted-Printable-like encoding) and B (base64). This alist specifies which charset should use which encoding.

rfc2047-encoding-function-alist

This is an alist of encoding / function pairs. The encodings are Q, B and nil.

rfc2047-q-encoding-alist

The Q encoding isn't quite the same for all headers. Some headers allow a narrower range of characters, and that is what this variable is for. It's an alist of header regexps / allowable character ranges.

rfc2047-encoded-word-regexp

When decoding words, this library looks for matches to this regexp.

Those were the variables, and these are this functions:

rfc2047-narrow-to-field

Narrow the buffer to the header on the current line.

rfc2047-encode-message-header

Should be called narrowed to the header of a message. Encodes according to rfc2047-header-encoding-alist.

rfc2047-encode-region

Encodes all encodable words in the region specified.

rfc2047-encode-string

Encode a string and return the results.

rfc2047-decode-region

Decode the encoded words in the region.

rfc2047-decode-string

Decode a string and return the results.