email.header.Header.append()

append(s, charset=None, errors='strict')

Append the string s to the MIME header.

Optional charset, if given, should be a Charset instance (see email.charset) or the name of a character set, which will be converted to a Charset instance. A value of None (the default) means that the charset given in the constructor is used.

s may be an instance of bytes or str. If it is an instance of bytes, then charset is the encoding of that byte string, and a UnicodeError will be raised if the string cannot be decoded with that character set.

If s is an instance of str, then charset is a hint specifying the character set of the characters in the string.

In either case, when producing an RFC 2822-compliant header using RFC 2047 rules, the string will be encoded using the output codec of the charset. If the string cannot be encoded using the output codec, a UnicodeError will be raised.

Optional errors is passed as the errors argument to the decode call if s is a byte string.