Send mail. The required arguments are an :rfc:`822` from-address string, a list
of :rfc:`822` to-address strings (a bare string will be treated as a list with 1
address), and a message string. The caller may pass a list of ESMTP options
- (such as ``8bitmime``) to be used in ``MAIL FROM`` commands as *mail_options*.
+ (such as ``"8bitmime"``) to be used in ``MAIL FROM`` commands as *mail_options*.
ESMTP options (such as ``DSN`` commands) that should be used with all ``RCPT``
- commands can be passed as *rcpt_options*. (If you need to use different ESMTP
+ commands can be passed as *rcpt_options*. Each option should be passed as a string
+ containing the full text of the option, including any potential key
+ (for instance, ``"NOTIFY=SUCCESS,FAILURE"``). (If you need to use different ESMTP
options to different recipients you have to use the low-level methods such as
:meth:`!mail`, :meth:`!rcpt` and :meth:`!data` to send the message.)