mimelib is a collection of useful functions to deal with mime-encoded data.


Install with npm

npm install mimelib


var mimelib = require("mimelib");



Folds a long line according to the RFC 5322 http://tools.ietf.org/html/rfc5322#section-2.1.1

mimelib.foldLine(str [, maxLength][, foldAnywhere][, afterSpace]) -> String
  • str (String): mime string that might need folding
  • maxLength (Number): max length for a line, defaults to 78
  • foldAnywhere (Boolean): can fold at any location (ie. in base64)
  • afterSpace (Boolean): If true fold after the space

For example:

Content-Type: multipart/alternative; boundary="----zzzz----"

will become

Content-Type: multipart/alternative;


Encodes a string into mime encoded word format http://en.wikipedia.org/wiki/MIME#Encoded-Word (see also decodeMimeWord)

mimelib.encodeMimeWord = function(str [, encoding][, charset])
  • str (String): String to be encoded
  • encoding (String): Encoding Q for quoted printable or B (def.) for base64
  • charset (String): Charset to be used

For example:

See on õhin test

Becomes with UTF-8 and Quoted-printable encoding



Decodes a string from mime encoded word format (see also encodeMimeWord)

mimelib.decodeMimeWord(str) -> String
  • str (String): String to be decoded

For example


will become

See on õhin test


Encodes a string into Quoted-printable format (see also decodeQuotedPrintable)

mimelib.encodeQuotedPrintable(str [, mimeWord][, charset]) -> String
  • str (String): String to be encoded into Quoted-printable
  • mimeWord (Boolean): Deprecated, has no effect, ignore it
  • charset (String): Destination charset, defaults to UTF-8


Decodes a string from Quoted-printable format (see also encodeQuotedPrintable)

mimelib.decodeQuotedPrintable(str [, mimeWord][, charset]) -> String
  • str (String): String to be decoded
  • mimeWord (Boolean): Deprecated, has no effect, ignore it
  • charset (String): Charset to be used, defaults to UTF-8


Encodes a string into Base64 format. Base64 is mime-word safe (see also decodeBase64)

mimelib.encodeBase64(str [, charset]) -> String
  • str (String): String to be encoded into Base64
  • charset (String): Destination charset, defaults to UTF-8


Decodes a string from Base64 format. Base64 is mime-word safe (see also encodeBase64)

NB! Always returns UTF-8

mimelib.decodeBase64(str) -> String
  • str (String): String to be decoded from Base64
  • charset (String): Source charset, defaults to UTF-8


Parses header lines into an array of objects (see parseHeaderLine)

mimelib.parseHeaders(headers) -> Array
  • headers (String): header section of the e-mail


var headers = [
    "From: andris@node.ee",
    "To: juulius@node.ee",
    "To: juulius2@node.ee",
    "Content-type: text/html;",
    "    charset=utf-8"

Results in

{"from": [ 'andris@node.ee' ],
 "to": [ 'juulius@node.ee', 'juulius2@node.ee' ],
 "content-type": [ 'text/html;    charset=utf-8' ] }


Parses names and addresses from a from, to, cc or bcc line

mimelib.parseAddresses(addresses) -> Array
  • addresses (String): string with comma separated e-mail addresses


var to = '"Andris Reinman" <andris@node.ee>, juulius@node.ee'

Results in

[{ address: 'andris@node.ee', name: 'Andris Reinman' },
 { address: 'juulius@node.ee', name: false }]


Parses mime-words into UTF-8 strings

mimelib.parseMimeWords(str) -> String
  • str (String): string to be parsed, if includes any mime words, then these are converted to UTF-8 strings

For example:

mimelib.parseMimeWords("Hello: =?UTF-8?Q?Seeon=C3=B5hin_test?=");

Results in

"Hello: See on õhin test"


Parses a header line to search for additional parameters.

mimelib.parseHeaderLine(line) -> Object
  • line (String): a line from a message headers

For example:

mimelib.parseHeaderLine("text/plain; charset=utf-8")imelib

Results in

{"defaultValue": 'text/plain',
 "charset": 'utf-8' }


NB! this feature is deprecated, use mime module instead to detect content types and extensions

mimelib.contentTypes is an object to provide content type strings for common file extensions

mimelib.contentTypes["xls"]; // "application/vnd.ms-excel"

iconv support

By default only iconv-lite support is bundled. If you need node-iconv support, you need to add it as an additional dependency for your project:

    "mimelib": "",
    "iconv": ""


mimelib license is