Fix sending by email not working on computers with non-ascii hostnames. Fixes #1256549 [E-mailing has problems on French Windows installation](https://bugs.launchpad.net/calibre/+bug/1256549)

src/calibre/utils/smtp.py

@@ -9,8 +9,9 @@ This module implements a simple commandline SMTP client that supports:
   * Background delivery with failures being saved in a maildir mailbox
 '''
 
-import sys, traceback, os
+import sys, traceback, os, socket
 from calibre import isbytestring
+from calibre.utils.filenames import ascii_text
 
 def create_mail(from_, to, subject, text=None, attachment_data=None,
                  attachment_type=None, attachment_name=None):
@@ -61,12 +62,34 @@ def get_mx(host, verbose=0):
                                       int(getattr(y, 'preference', sys.maxint))))
     return [str(x.exchange) for x in answers if hasattr(x, 'exchange')]
 
+def safe_localhost():
+    # RFC 2821 says we should use the fqdn in the EHLO/HELO verb, and
+    # if that can't be calculated, that we should use a domain literal
+    # instead (essentially an encoded IP address like [A.B.C.D]).
+    fqdn = socket.getfqdn()
+    if '.' in fqdn:
+        # Some mail servers have problems with non-ascii local hostnames, see
+        # https://bugs.launchpad.net/bugs/1256549
+        try:
+            local_hostname = ascii_text(fqdn)
+        except:
+            local_hostname = 'localhost.localdomain'
+    else:
+        # We can't find an fqdn hostname, so use a domain literal
+        addr = '127.0.0.1'
+        try:
+            addr = socket.gethostbyname(socket.gethostname())
+        except socket.gaierror:
+            pass
+        local_hostname = '[%s]' % addr
+    return local_hostname
+
 def sendmail_direct(from_, to, msg, timeout, localhost, verbose,
         debug_output=None):
     import calibre.utils.smtplib as smtplib
     hosts = get_mx(to.split('@')[-1].strip(), verbose)
     timeout=None  # Non blocking sockets sometimes don't work
-    kwargs = dict(timeout=timeout, local_hostname=localhost)
+    kwargs = dict(timeout=timeout, local_hostname=localhost or safe_localhost())
     if debug_output is not None:
         kwargs['debug_to'] = debug_output
     s = smtplib.SMTP(**kwargs)
@@ -96,7 +119,7 @@ def sendmail(msg, from_, to, localhost=None, verbose=0, timeout=None,
     cls = smtplib.SMTP_SSL if encryption == 'SSL' else smtplib.SMTP
     timeout = None  # Non-blocking sockets sometimes don't work
     port = int(port)
-    kwargs = dict(timeout=timeout, local_hostname=localhost)
+    kwargs = dict(timeout=timeout, local_hostname=localhost or safe_localhost())
     if debug_output is not None:
         kwargs['debug_to'] = debug_output
     s = cls(**kwargs)
@@ -203,7 +226,6 @@ def main(args=sys.argv):
     parser = option_parser()
     opts, args = parser.parse_args(args)
 
-
     if len(args) > 1:
         if len(args) < 4:
             print ('You must specify the from address, to address and body text'