diff --git a/addons/mail/models/mail_alias.py b/addons/mail/models/mail_alias.py
index b1f61503476..bebc4719357 100644
--- a/addons/mail/models/mail_alias.py
+++ b/addons/mail/models/mail_alias.py
@@ -156,21 +156,54 @@ class Alias(models.Model):
         """When an alias name appears to already be an email, we keep the local
         part only. A sanitizing / cleaning is also performed on the name. If
         name already exists an UserError is raised. """
-        sanitized_names = []
-        for name in names:
+
+        def _sanitize_alias_name(name):
+            """ Cleans and sanitizes the alias name """
             sanitized_name = remove_accents(name).lower().split('@')[0]
             sanitized_name = re.sub(r'[^\w+.]+', '-', sanitized_name)
             sanitized_name = sanitized_name.encode('ascii', errors='replace').decode()
-            sanitized_names.append(sanitized_name)
+            return sanitized_name
+
+        sanitized_names = [_sanitize_alias_name(name) for name in names]
 
         catchall_alias = self.env['ir.config_parameter'].sudo().get_param('mail.catchall.alias')
         bounce_alias = self.env['ir.config_parameter'].sudo().get_param('mail.bounce.alias')
+        alias_domain = self.env["ir.config_parameter"].sudo().get_param("mail.catchall.domain")
+
+        # matches catchall or bounce alias
+        for sanitized_name in sanitized_names:
+            if sanitized_name in [catchall_alias, bounce_alias]:
+                matching_alias_name = '%s@%s' % (sanitized_name, alias_domain) if alias_domain else sanitized_name
+                raise UserError(
+                    _('The e-mail alias %(matching_alias_name)s is already used as %(alias_duplicate)s alias. Please choose another alias.',
+                      matching_alias_name=matching_alias_name,
+                      alias_duplicate=_('catchall') if sanitized_name == catchall_alias else _('bounce'))
+                )
+
+        # matches existing alias
         domain = [('alias_name', 'in', sanitized_names)]
         if self:
             domain += [('id', 'not in', self.ids)]
-        if any(sanitized_name in [catchall_alias, bounce_alias] for sanitized_name in sanitized_names) or self.search_count(domain):
-            raise UserError(_('The e-mail alias is already used. Please enter another one.'))
-        return sanitized_names
+        matching_alias = self.search(domain, limit=1)
+        if not matching_alias:
+            return sanitized_names
+
+        sanitized_alias_name = _sanitize_alias_name(matching_alias.alias_name)
+        matching_alias_name = '%s@%s' % (sanitized_alias_name, alias_domain) if alias_domain else sanitized_alias_name
+        if matching_alias.alias_parent_model_id and matching_alias.alias_parent_thread_id:
+            # If parent model and parent thread ID both are set, display document name also in the warning
+            document_name = self.env[matching_alias.alias_parent_model_id.model].sudo().browse(matching_alias.alias_parent_thread_id).display_name
+            raise UserError(
+                _('The e-mail alias %(matching_alias_name)s is already used by the %(document_name)s %(model_name)s. Choose another alias or change it on the other document.',
+                  matching_alias_name=matching_alias_name,
+                  document_name=document_name,
+                  model_name=matching_alias.alias_parent_model_id.name)
+                )
+        raise UserError(
+            _('The e-mail alias %(matching_alias_name)s is already linked with %(alias_model_name)s. Choose another alias or change it on the linked model.',
+              matching_alias_name=matching_alias_name,
+              alias_model_name=matching_alias.alias_model_id.name)
+        )
 
     def open_document(self):
         if not self.alias_model_id or not self.alias_force_thread_id: