diff --git a/addons/crm/crm.py b/addons/crm/crm.py
index df6d5e12b66..5953500dcec 100644
--- a/addons/crm/crm.py
+++ b/addons/crm/crm.py
@@ -125,7 +125,7 @@ class crm_case_section(osv.osv):
         'note': fields.text('Description'),
         'working_hours': fields.float('Working Hours', digits=(16,2 )),
         'stage_ids': fields.many2many('crm.case.stage', 'section_stage_rel', 'section_id', 'stage_id', 'Stages'),
-        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="cascade", required=True,
+        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="restrict", required=True,
                                     help="The email address associated with this team. New emails received will automatically "
                                          "create new leads assigned to the team."),
     }
diff --git a/addons/hr_recruitment/hr_recruitment.py b/addons/hr_recruitment/hr_recruitment.py
index 6dfc0869947..d97a6ee80ec 100644
--- a/addons/hr_recruitment/hr_recruitment.py
+++ b/addons/hr_recruitment/hr_recruitment.py
@@ -496,7 +496,7 @@ class hr_job(osv.osv):
     _inherits = {'mail.alias': 'alias_id'}
     _columns = {
         'survey_id': fields.many2one('survey', 'Interview Form', help="Choose an interview form for this job position and you will be able to print/answer this interview from all applicants who apply for this job"),
-        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="cascade", required=True,
+        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="restrict", required=True,
                                     help="Email alias for this job position. New emails will automatically "
                                          "create new applicants for this job position."),
     }
diff --git a/addons/mail/mail_group.py b/addons/mail/mail_group.py
index 977608f487e..481109a8ebe 100644
--- a/addons/mail/mail_group.py
+++ b/addons/mail/mail_group.py
@@ -76,7 +76,7 @@ class mail_group(osv.Model):
             help="Small-sized photo of the group. It is automatically "\
                  "resized as a 64x64px image, with aspect ratio preserved. "\
                  "Use this field anywhere a small image is required."),
-        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="cascade", required=True,
+        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="restrict", required=True,
             help="The email address associated with this group. New emails received will automatically "
                  "create new topics."),
     }
diff --git a/addons/mail/res_users.py b/addons/mail/res_users.py
index f7c91939b98..c6a935a62b7 100644
--- a/addons/mail/res_users.py
+++ b/addons/mail/res_users.py
@@ -34,7 +34,7 @@ class res_users(osv.Model):
     _inherits = {'mail.alias': 'alias_id'}
 
     _columns = {
-        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="cascade", required=True,
+        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="restrict", required=True,
             help="Email address internally associated with this user. Incoming "\
                  "emails will appear in the user's notifications."),
     }
diff --git a/addons/project/project.py b/addons/project/project.py
index 8ffd64e0506..d7794a02fea 100644
--- a/addons/project/project.py
+++ b/addons/project/project.py
@@ -281,7 +281,7 @@ class project(osv.osv):
         'type_ids': fields.many2many('project.task.type', 'project_task_type_rel', 'project_id', 'type_id', 'Tasks Stages', states={'close':[('readonly',True)], 'cancelled':[('readonly',True)]}),
         'task_count': fields.function(_task_count, type='integer', string="Open Tasks"),
         'color': fields.integer('Color Index'),
-        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="cascade", required=True,
+        'alias_id': fields.many2one('mail.alias', 'Alias', ondelete="restrict", required=True,
                                     help="Internal email associated with this project. Incoming emails are automatically synchronized"
                                          "with Tasks (or optionally Issues if the Issue Tracker module is installed)."),
         'alias_model': fields.selection(_alias_models, "Alias Model", select=True, required=True,