diff -r 02d467e4fbab -r 0684790fff7c VirtualMailManager/__init__.py
--- a/VirtualMailManager/__init__.py	Wed Feb 10 08:55:51 2010 +0000
+++ b/VirtualMailManager/__init__.py	Thu Feb 11 03:08:11 2010 +0000
@@ -12,8 +12,8 @@
 from encodings.idna import ToASCII, ToUnicode
 
 from VirtualMailManager.constants.ERROR import \
-     DOMAIN_INVALID, DOMAIN_TOO_LONG, NOT_EXECUTABLE, NO_SUCH_BINARY, \
-     NO_SUCH_DIRECTORY
+     DOMAIN_INVALID, DOMAIN_TOO_LONG, LOCALPART_INVALID, LOCALPART_TOO_LONG, \
+     NOT_EXECUTABLE, NO_SUCH_BINARY, NO_SUCH_DIRECTORY
 from VirtualMailManager.constants.VERSION import *
 from VirtualMailManager.Exceptions import VMMException
 
@@ -24,8 +24,8 @@
     # version information from VERSION
     '__author__', '__date__', '__version__',
     # error codes
-    'ENCODING', 'ace2idna', 'chk_domainname', 'exec_ok', 'expand_path',
-    'get_unicode', 'idn2ascii', 'is_dir',
+    'ENCODING', 'ace2idna', 'check_domainname', 'check_localpart', 'exec_ok',
+    'expand_path', 'get_unicode', 'idn2ascii', 'is_dir',
 ]
 
 
@@ -37,18 +37,26 @@
     locale.setlocale(locale.LC_ALL, 'C')
 ENCODING = locale.nl_langinfo(locale.CODESET)
 
-RE_ASCII_CHARS = """^[\x20-\x7E]*$"""
-RE_DOMAIN = """^(?:[a-z0-9-]{1,63}\.){1,}[a-z]{2,6}$"""
+RE_ASCII_CHARS = r"^[\x20-\x7E]*$"
+RE_DOMAIN = r"^(?:[a-z0-9-]{1,63}\.){1,}[a-z]{2,6}$"
+RE_LOCALPART = r"[^\w!#$%&'\*\+-\.\/=?^_`{\|}~]"
+
+
+# there may be many domain and e-mail address checks
+re_obj_domain = re.compile(RE_DOMAIN)
+re_obj_localpart = re.compile(RE_LOCALPART)
 
 
 gettext.install('vmm', '/usr/local/share/locale', unicode=1)
 
+
 def get_unicode(string):
     """Converts `string` to `unicode`, if necessary."""
     if isinstance(string, unicode):
         return string
     return unicode(string, ENCODING, 'replace')
 
+
 def expand_path(path):
     """Expands paths, starting with ``.`` or ``~``, to an absolute path."""
     if path.startswith('.'):
@@ -57,6 +65,7 @@
         return os.path.expanduser(path)
     return path
 
+
 def is_dir(path):
     """Checks if ``path`` is a directory.
 
@@ -64,10 +73,11 @@
     """
     path = expand_path(path)
     if not os.path.isdir(path):
-        raise VMMException(_(u'“%s” is not a directory') % get_unicode(path),
-                           NO_SUCH_DIRECTORY)
+        raise VMMException(_(u'“%s” is not a directory') %
+                            get_unicode(path), NO_SUCH_DIRECTORY)
     return path
 
+
 def exec_ok(binary):
     """Checks if the ``binary`` exists and if it is executable.
 
@@ -83,27 +93,49 @@
                            get_unicode(binary), NOT_EXECUTABLE)
     return binary
 
+
 def idn2ascii(domainname):
     """Converts the idn domain name `domainname` into punycode."""
     return '.'.join([ToASCII(lbl) for lbl in domainname.split('.') if lbl])
 
+
 def ace2idna(domainname):
     """Converts the domain name `domainname` from ACE according to IDNA."""
     return u'.'.join([ToUnicode(lbl) for lbl in domainname.split('.') if lbl])
 
-def chk_domainname(domainname):
+
+def check_domainname(domainname):
     """Returns the validated domain name `domainname`.
 
     It also converts the name of the domain from IDN to ASCII, if necessary.
 
-    Throws an VMMException, if the domain name is too long or doesn't look
+    Throws an `VMMException`, if the domain name is too long or doesn't look
     like a valid domain name (label.label.label).
     """
-    if not re.match(RE_ASCII_CHARS, domainname):
+    if not re_obj_domain.match(domainname):
         domainname = idn2ascii(domainname)
     if len(domainname) > 255:
-        raise VMMException(_(u'The domain name is too long.'), DOMAIN_TOO_LONG)
-    if not re.match(RE_DOMAIN, domainname):
-        raise VMMException(_(u'The domain name “%s” is invalid.') % domainname,
+        raise VMMException(_(u'The domain name is too long'), DOMAIN_TOO_LONG)
+    if not re_obj_domain.match(domainname):
+        raise VMMException(_(u'The domain name %r is invalid') % domainname,
                            DOMAIN_INVALID)
     return domainname
+
+
+def check_localpart(localpart):
+    """Returns the validated local-part *localpart*.
+
+    Throws a `VMMException` if the local-part is too long or contains
+    invalid characters.
+    """
+    if len(localpart) > 64:
+        raise VMMException(_(u'The local-part %r is too long') % localpart,
+                           LOCALPART_TOO_LONG)
+    invalid_chars = set(re_obj_localpart.findall(localpart))
+    if invalid_chars:
+        i_chars = u''.join((u'"%s" ' % c for c in invalid_chars))
+        raise VMMException(_(u"The local-part %(l_part)r contains invalid \
+characters: %(i_chars)s") %
+                           {'l_part': localpart, 'i_chars': i_chars},
+                           LOCALPART_INVALID)
+    return localpart