Latest version by The Dragon, who writes:

I did some bugfixes, and fixed a major problem with the esmtp suport (I
think the person who did that part misunderstood RFC1869) Some of the
interface fer esmtp-related things has changed as a result.

I also added some documentation to the SMTP class' docstring.

Lib/smtplib.py

@@ -3,14 +3,20 @@
 
 Author: The Dragon De Monsyne <dragondm@integral.org>
 ESMTP support, test code and doc fixes added by
-Eric S. Raymond <esr@thyrsus.com>
+    Eric S. Raymond <esr@thyrsus.com>
 Better RFC 821 compliance (MAIL and RCPT, and CRLF in data)
-by Carey Evans <c.evans@clear.net.nz>, for picky mail servers.
+    by Carey Evans <c.evans@clear.net.nz>, for picky mail servers.
    
 (This was modified from the Python 1.5 library HTTP lib.)
 
 This should follow RFC 821 (SMTP) and RFC 1869 (ESMTP).
 
+Notes:
+
+Please remember, when doing ESMTP, that the names of the SMTP service
+extensions are NOT the same thing as the option keyords for the RCPT
+and MAIL commands!
+
 Example:
 
 >>> import smtplib
@@ -34,7 +40,8 @@ End of HELP info
 """
 
 import socket
-import string,re
+import string, re
+import rfc822
 
 SMTP_PORT = 25
 CRLF="\r\n"
@@ -48,41 +55,61 @@ SMTPDataError="Error transmitting message data"
 def quoteaddr(addr):
     """Quote a subset of the email addresses defined by RFC 821.
 
-    Technically, only a <mailbox> is allowed.  In addition,
+    Should be able to handle anything rfc822.parseaddr can handle."""
-    email addresses without a domain are permitted.
 
-    Addresses will not be modified if they are already quoted
+    m=None
-    (actually if they begin with '<' and end with '>'."""
-    if re.match('(?s)\A<.*>\Z', addr):
-        return addr
-
-    localpart = None
-    domain = ''
     try:
-        at = string.rindex(addr, '@')
+        m=rfc822.parseaddr(addr)[1]
-        localpart = addr[:at]
+    except AttributeError:
-        domain = addr[at:]
+        pass
-    except ValueError:
+    if not m:
-        localpart = addr
+        #something weird here.. punt -ddm
-
+        return addr
-    pat = re.compile(r'([<>()\[\]\\,;:@\"\001-\037\177])')
+    else:
-    return '<%s%s>' % (pat.sub(r'\\\1', localpart), domain)
+        return "<%s>" % m
 
 def quotedata(data):
     """Quote data for email.
 
-    Double leading '.', and change Unix newline '\n' into
+    Double leading '.', and change Unix newline '\n', or Mac '\r' into
     Internet CRLF end-of-line."""
     return re.sub(r'(?m)^\.', '..',
-                  re.sub(r'\r?\n', CRLF, data))
+        re.sub(r'(?:\r\n|\n|\r(?!\n))', CRLF, data))
 
 class SMTP:
-    """This class manages a connection to an SMTP or ESMTP server."""
+    """This class manages a connection to an SMTP or ESMTP server.
+    SMTP Objects:
+        SMTP objects have the following attributes:    
+            helo_resp 
+                This is the message given by the server in responce to the 
+                most recent HELO command.
+                
+            ehlo_resp
+                This is the message given by the server in responce to the 
+                most recent EHLO command. This is usually multiline.
+
+            does_esmtp 
+                This is a True value _after you do an EHLO command_, if the
+                server supports ESMTP.
+
+            esmtp_features 
+                This is a dictionary, which, if the server supports ESMTP,
+                will  _after you do an EHLO command_, contain the names of the
+                SMTP service  extentions this server supports, and their 
+                parameters (if any).
+                Note, all extention names are mapped to lower case in the 
+                dictionary. 
+
+        For method docs, see each method's docstrings. In general, there is 
+            a method of the same name to preform each SMTP comand, and there 
+            is a method called 'sendmail' that will do an entiere mail 
+            transaction."""
+
     debuglevel = 0
     file = None
     helo_resp = None
     ehlo_resp = None
-    esmtp_features = []
+    does_esmtp = 0
 
     def __init__(self, host = '', port = 0):
         """Initialize a new instance.
@@ -92,6 +119,7 @@ class SMTP:
         to connect.  By default, smtplib.SMTP_PORT is used.
 
         """
+        self.esmtp_features = {}
         if host: self.connect(host, port)
     
     def set_debuglevel(self, debuglevel):
@@ -103,17 +131,12 @@ class SMTP:
         """
         self.debuglevel = debuglevel
 
-    def verify(self, address):
-        """ SMTP 'verify' command. Checks for address validity. """
-        self.putcmd("vrfy", address)
-        return self.getreply()
-
     def connect(self, host='localhost', port = 0):
         """Connect to a host on a given port.
 
         If the hostname ends with a colon (`:') followed by a number,
-        that suffix will be stripped off and the number interpreted as
+	and there is no port specified,  that suffix will be stripped 
-        the port number to use.
+        off and the number interpreted as the port number to use.
 
         Note:  This method is automatically invoked by __init__,
         if a host is specified during instantiation.
@@ -138,7 +161,10 @@ class SMTP:
         """Send `str' to the server."""
         if self.debuglevel > 0: print 'send:', `str`
         if self.sock:
-            self.sock.send(str)
+	    try:
+                self.sock.send(str)
+	    except socket.error:
+                raise SMTPServerDisconnected
         else:
             raise SMTPServerDisconnected
  
@@ -148,7 +174,7 @@ class SMTP:
         str = '%s %s%s' % (cmd, args, CRLF)
         self.send(str)
     
-    def getreply(self, linehook=None):
+    def getreply(self):
         """Get a reply from the server.
         
         Returns a tuple consisting of:
@@ -168,8 +194,6 @@ class SMTP:
             #check if multiline resp
             if line[3:4]!="-":
                 break
-            elif linehook:
-                linehook(line)
         try:
             errcode = string.atoi(code)
         except(ValueError):
@@ -201,23 +225,35 @@ class SMTP:
 
     def ehlo(self, name=''):
         """ SMTP 'ehlo' command. Hostname to send for this command  
-        defaults to the FQDN of the local host """
+        defaults to the FQDN of the local host.  """
         name=string.strip(name)
         if len(name)==0:
                 name=socket.gethostbyaddr(socket.gethostname())[0]
         self.putcmd("ehlo",name)
-        (code,msg)=self.getreply(self.ehlo_hook)
+        (code,msg)=self.getreply()
+        # According to RFC1869 some (badly written) 
+        # MTA's will disconnect on an ehlo. Toss an exception if 
+        # that happens -ddm
+        if code == -1 and len(msg) == 0:
+            raise SMTPServerDisconnected
         self.ehlo_resp=msg
+        if code<>250:
+            return code
+        self.does_esmtp=1
+        #parse the ehlo responce -ddm
+	resp=string.split(self.ehlo_resp,'\n')
+        del resp[0]
+	for each in resp:
+            m=re.match(r'(?P<feature>[A-Za-z0-9][A-Za-z0-9\-]*)',each)
+            if m:
+                feature=string.lower(m.group("feature"))
+                params=string.strip(m.string[m.end("feature"):])
+                self.esmtp_features[feature]=params
         return code
 
-    def ehlo_hook(self, line):
+    def has_extn(self, opt):
-        # Interpret EHLO response lines
+        """Does the server support a given SMTP service extension?"""
-        if line[4] in string.uppercase+string.digits:
+        return self.esmtp_features.has_key(string.lower(opt))
-            self.esmtp_features.append(string.lower(string.strip(line)[4:]))
-
-    def has_option(self, opt):
-        """Does the server support a given SMTP option?"""
-        return opt in self.esmtp_features
 
     def help(self, args=''):
         """ SMTP 'help' command. Returns help text from server """
@@ -237,16 +273,18 @@ class SMTP:
 
     def mail(self,sender,options=[]):
         """ SMTP 'mail' command. Begins mail xfer session. """
-        if options:
+        optionlist = ''
-            options = " " + string.joinfields(options, ' ')
+        if options and self.does_esmtp:
-        else:
+            optionlist = string.join(options, ' ')
-            options = ''
+        self.putcmd("mail", "FROM:%s %s" % (quoteaddr(sender) ,optionlist))
-        self.putcmd("mail", "from:" + quoteaddr(sender) + options)
         return self.getreply()
 
-    def rcpt(self,recip):
+    def rcpt(self,recip,options=[]):
         """ SMTP 'rcpt' command. Indicates 1 recipient for this mail. """
-        self.putcmd("rcpt","to:%s" % quoteaddr(recip))
+        optionlist = ''
+        if options and self.does_esmtp:
+            optionlist = string.join(options, ' ')
+        self.putcmd("rcpt","TO:%s %s" % (quoteaddr(recip),optionlist))
         return self.getreply()
 
     def data(self,msg):
@@ -264,20 +302,35 @@ class SMTP:
             if self.debuglevel >0 : print "data:", (code,msg)
             return code
 
+    def vrfy(self, address):
+        return self.verify(address)
+
+    def verify(self, address):
+        """ SMTP 'verify' command. Checks for address validity. """
+        self.putcmd("vrfy", quoteaddr(address))
+        return self.getreply()
+
+    def expn(self, address):
+        """ SMTP 'verify' command. Checks for address validity. """
+        self.putcmd("expn", quoteaddr(address))
+        return self.getreply()
+
+
 #some useful methods
-    def sendmail(self,from_addr,to_addrs,msg,options=[]):
+    def sendmail(self,from_addr,to_addrs,msg,mail_options=[],rcpt_options=[]):
         """ This command performs an entire mail transaction. 
             The arguments are: 
                - from_addr : The address sending this mail.
                - to_addrs :  a list of addresses to send this mail to
                - msg : the message to send. 
-               - encoding : list of ESMTP options (such as 8bitmime)
+               - mail_options : list of ESMTP options (such as 8bitmime)
-
+                                for the mail command
+               - rcpt_options : List of ESMTP options (such as DSN commands)
+                               for all the rcpt commands
 	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
+        size and each of the specified options will be passed to it.  
-        option is in the feature set the server advertises).  If EHLO fails,
+        If EHLO fails, HELO will be tried and ESMTP options suppressed.
-        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 (either
@@ -309,21 +362,22 @@ class SMTP:
         if not self.helo_resp and not self.ehlo_resp:
             if self.ehlo() >= 400:
                 self.helo()
-        if self.esmtp_features:
-            self.esmtp_features.append('7bit')
         esmtp_opts = []
-        if 'size' in self.esmtp_features:
+        if self.does_esmtp:
-            esmtp_opts.append("size=" + `len(msg)`)
+            # Hmmm? what's this? -ddm
-        for option in options:
+            # self.esmtp_features['7bit']=""
-            if option in self.esmtp_features:
+            if self.has_extn('size'):
+                esmtp_opts.append("size=" + `len(msg)`)
+            for option in mail_options:
                 esmtp_opts.append(option)
+
         (code,resp) = self.mail(from_addr, esmtp_opts)
         if code <> 250:
             self.rset()
             raise SMTPSenderRefused
         senderrs={}
         for each in to_addrs:
-            (code,resp)=self.rcpt(each)
+            (code,resp)=self.rcpt(each, rcpt_options)
             if (code <> 250) and (code <> 251):
                 senderrs[each]=(code,resp)
         if len(senderrs)==len(to_addrs):