header_encode(header, charset='iso-8859-1', keep_eols=False, maxlinelen=76, eol='\n')
Encode a single header line with Base64 encoding in a given charset.
Defined in RFC 2045, this Base64 encoding is identical to normal Base64 encoding, except that each line must be intelligently wrapped (respecting the Base64 encoding), and subsequent lines must start with a space.
charset names the character set to use to encode the header. It defaults to iso-8859-1.
End-of-line characters (\r, \n, \r\n) will be automatically converted to the canonical email line separator \r\n unless the keep_eols parameter is True (the default is False).
Each line of the header will be terminated in the value of eol, which defaults to "\n". Set this to "\r\n" if you are using the result of this function directly in email.
The resulting string will be in the form:
"=?charset?b?WW/5ciBtYXp66XLrIHf8eiBhIGhhbXBzdGHuciBBIFlv+XIgbWF6euly?=\n =?charset?b?6yB3/HogYSBoYW1wc3Rh7nIgQkMgWW/5ciBtYXp66XLrIHf8eiBhIGhh?="
with each line wrapped at, at most, maxlinelen characters (defaults to 76 characters).