--- a/management/univention-directory-manager-modules/modules/univention/admin/__init__.py	
+++ a/management/univention-directory-manager-modules/modules/univention/admin/__init__.py	
@@ -173,7 +173,7 @@ def __init__(self, short_description='', long_description='', syntax=None,
 			license=[], required=0, may_change=1, identifies=0, unique=0, default=None,
 			dontsearch=0, show_in_lists=0, editable=1, configObjectPosition=None,
 			configAttributeName=None, include_in_default_search=0, nonempty_is_default=False,
-			readonly_when_synced=False, size=None):
+			readonly_when_synced=False, size=None, set_default_value_when_opening=False):
 		self.short_description=short_description
 		self.long_description=long_description
 		if type(syntax) == types.ClassType:
@@ -202,6 +202,7 @@ def __init__(self, short_description='', long_description='', syntax=None,
 		self.nonempty_is_default = nonempty_is_default
 		self.readonly_when_synced = readonly_when_synced
 		self.size = size
+		self.set_default_value_when_opening = set_default_value_when_opening
 
 	def new(self):
 		if self.multivalue:
--- a/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py	
+++ a/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py	
@@ -605,8 +605,11 @@ def call_udm_property_hook(self, hookname, module, changes = None):
 		return changes
 
 	def open(self):
-		self.exceptions=[]
+		self.exceptions = []
 		self.call_udm_property_hook('hook_open', self)
+		for name, property_ in self.descriptions.iteritems():
+			if property_.set_default_value_when_opening and self.has_key(name) and not self[name]:
+				self[name] = property_.default(self)
 		self.save()
 
 	def _remove_option( self, name ):
--- a/management/univention-directory-manager-modules/modules/univention/admin/modules.py	
+++ a/management/univention-directory-manager-modules/modules/univention/admin/modules.py	
@@ -352,7 +352,8 @@ def update_extended_attributes(lo, module, position):
 			dontsearch = doNotSearch,
 			identifies = 0,
 			default = propertyDefault,
-			editable = editable
+			editable = editable,
+			set_default_value_when_opening='1' in attrs.get('univentionUDMPropertySetDefaultOnOpen', []),
 		)
 
 		# add LDAP mapping