diff --git a/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py b/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
index 0ab84660f8..2a5a7f8816 100644
--- a/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
+++ b/management/univention-directory-manager-modules/modules/univention/admin/handlers/users/user.py
@@ -1891,7 +1891,7 @@ class object(univention.admin.handlers.simpleLdap):
 
 		# get lock for mailPrimaryAddress
 		if not self.exists() or self.hasChanged('mailPrimaryAddress'):
-			if self['mailPrimaryAddress']:
+			if self['mailPrimaryAddress'] and self['mailPrimaryAddress'].lower() != self.oldinfo.get('mailPrimaryAddress', '').lower():
 				try:
 					self.alloc.append(('mailPrimaryAddress', univention.admin.allocators.request(self.lo, self.position, 'mailPrimaryAddress', value=self['mailPrimaryAddress'])))
 				except univention.admin.uexceptions.noLock: