12.2.7 Miscellaneous utilities

There are several useful utilities provided with the email package.

quote(str): Return a new string with backslashes in str replaced by two backslashes and double quotes replaced by backslash-double quote.

unquote(str): Return a new string which is an unquoted version of str. If str ends and begins with double quotes, they are stripped off. Likewise if str ends and begins with angle brackets, they are stripped off.

parseaddr(address): Parse address - which should be the value of some address-containing field such as To: or Cc: - into its constituent realname and email address parts. Returns a tuple of that information, unless the parse fails, in which case a 2-tuple of (None, None) is returned.

dump_address_pair(pair): The inverse of parseaddr(), this takes a 2-tuple of the form (realname, email_address) and returns the string value suitable for a To: or Cc: header. If the first element of pair is false, then the second element is returned unmodified.

getaddresses(fieldvalues)

This method returns a list of 2-tuples of the form returned by parseaddr(). fieldvalues is a sequence of header field values as might be returned by Message.getall(). Here's a simple example that gets all the recipients of a message:

from email.Utils import getaddresses

tos = msg.get_all('to', [])
ccs = msg.get_all('cc', [])
resent_tos = msg.get_all('resent-to', [])
resent_ccs = msg.get_all('resent-cc', [])
all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)

decode(s): This method decodes a string according to the rules in RFC 2047. It returns the decoded string as a Python unicode string.

encode(s[, charset[, encoding]]): This method encodes a string according to the rules in RFC 2047. It is not actually the inverse of decode() since it doesn't handle multiple character sets or multiple string parts needing encoding. In fact, the input string s must already be encoded in the charset character set (Python can't reliably guess what character set a string might be encoded in). The default charset is "iso-8859-1".
encoding must be either the letter "q" for Quoted-Printable or "b" for Base64 encoding. If neither, a ValueError is raised. Both the charset and the encoding strings are case-insensitive, and coerced to lower case in the returned string.

parsedate(date): Attempts to parse a date according to the rules in RFC 2822. however, some mailers don't follow that format as specified, so parsedate() tries to guess correctly in such cases. date is a string containing an RFC 2822 date, such as "Mon, 20 Nov 1995 19:12:08 -0500". If it succeeds in parsing the date, parsedate() returns a 9-tuple that can be passed directly to time.mktime(); otherwise None will be returned. Note that fields 6, 7, and 8 of the result tuple are not usable.

parsedate_tz(date): Performs the same function as parsedate(), but returns either None or a 10-tuple; the first 9 elements make up a tuple that can be passed directly to time.mktime(), and the tenth is the offset of the date's timezone from UTC (which is the official term for Greenwich Mean Time)^12.3. If the input string has no timezone, the last element of the tuple returned is None. Note that fields 6, 7, and 8 of the result tuple are not usable.

mktime_tz(tuple): Turn a 10-tuple as returned by parsedate_tz() into a UTC timestamp. It the timezone item in the tuple is None, assume local time. Minor deficiency: mktime_tz() interprets the first 8 elements of tuple as a local time and then compensates for the timezone difference. This may yield a slight error around changes in daylight savings time, though not worth worrying about for common use.

formatdate([timeval[, localtime]])

Returns a date string as per Internet standard RFC 2822, e.g.:

Fri, 09 Nov 2001 01:08:47 -0000

Optional timeval if given is a floating point time value as accepted by time.gmtime() and time.localtime(), otherwise the current time is used.

Optional localtime is a flag that when true, interprets timeval, and returns a date relative to the local timezone instead of UTC, properly taking daylight savings time into account.

Footnotes

... Time)^12.3: Note that the sign of the timezone offset is the opposite of the sign of the time.timezone variable for the same timezone; the latter variable follows the POSIX standard while this module follows RFC 2822.

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