##
11.9.1 SMTP Objects

An `SMTP` instance has the following methods:

`set_debuglevel` (level)
  Set the debug output level. A true value for level results in debug messages for connection and for all messages sent to and received from the server.

`connect` ([host[, port]])
  Connect to a host on a given port. The defaults are to connect to the local host at the standard SMTP port (25).

  If the hostname ends with a colon ("`:`") followed by a number, that suffix will be stripped off and the number interpreted as the port number to use.

  Note: This method is automatically invoked by the constructor if a host is specified during instantiation.

`docmd` (cmd, [, argstring])
  Send a command cmd to the server. The optional argument argstring is simply concatenated to the command, separated by a space.

  This returns a 2-tuple composed of a numeric response code and the actual response line (multiline responses are joined into one long line.)

  In normal operation it should not be necessary to call this method explicitly. It is used to implement other methods and may be useful for testing private extensions.

  If the connection to the server is lost while waiting for the reply, `SMTPServerDisconnected` will be raised.

`helo` ([hostname])
  Identify yourself to the SMTP server using "`HELO`". The hostname argument defaults to the fully qualified domain name of the local host.

  In normal operation it should not be necessary to call this method explicitly. It will be implicitly called by the `sendmail()` when necessary.

`ehlo` ([hostname])
  Identify yourself to an ESMTP server using "`EHLO`". The hostname argument defaults to the fully qualified domain name of the local host. Examine the response for ESMTP option and store them for use by `has_option()`.

  Unless you wish to use `has_option()` before sending mail, it should not be necessary to call this method explicitly. It will be implicitly called by `sendmail()` when necessary.

`has_extn` (name)
  Return `1` if name is in the set of SMTP service extensions returned by the server, `0` otherwise. Case is ignored.

`verify` (address)
  Check the validity of an address on this server using SMTP "`VRFY`". Returns a tuple consisting of code 250 and a full RFC 822 address (including human name) if the user address is valid. Otherwise returns an SMTP error code of 400 or greater and an error string.

  Note: many sites disable SMTP "`VRFY`" in order to foil spammers.

`sendmail` (from_addr, to_addrs, msg[, mail_options, rcpt_options])
  Send mail. The required arguments are an RFC 822 from-address string, a list of RFC 822 to-address strings, 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. 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 options to different recipients you have to use the low-level methods such as `mail`, `rcpt` and `data` to send the message.)

  If there has been no previous "`EHLO`" or "`HELO`" command this session, this method tries ESMTP "`EHLO`" first. If the server does ESMTP, message size and each of the specified options will be passed to it (if the option is in the feature set the server advertises). If "`EHLO`" fails, "`HELO`" will be tried and ESMTP options suppressed.

  This method will return normally if the mail is accepted for at least one recipient. Otherwise it will throw an exception. That is, if this method does not throw an exception, then someone should get your mail. If this method does not throw an exception, it returns a dictionary, with one entry for each recipient that was refused. Each entry contains a tuple of the SMTP error code and the accompanying error message sent by the server.

  This method may raise the following exceptions:

  `SMTPRecipientsRefused`
    All recipients were refused. Nobody got the mail. The recipients attribute of the exception object is a dictionary with information about the refused recipients (like the one returned when at least one recipient was accepted).

  `SMTPHeloError`
    The server didn't reply properly to the helo greeting.

  `SMTPSenderRefused`
    The server didn't accept the from_addr.

  `SMTPDataError`
    The server replied with an unexpected error code (other than a refusal of a recipient).

  Unless otherwise noted the connection will be open even after an exception is raised.

`quit` ()
  Terminate the SMTP session and close the connection.

Low-level methods corresponding to the standard SMTP/ESMTP commands "`HELP`", "`RSET`", "`NOOP`", "`MAIL`", "`RCPT`", and "`DATA`" are also supported. Normally these do not need to be called directly, so they are not documented here. For details, consult the module code.