--- /usr/share/pyshared/univention/googleapps/handler.py.old	2019-04-18 12:18:19.888000000 +0200
+++ /usr/share/pyshared/univention/googleapps/handler.py	2019-04-18 12:18:27.424000000 +0200
@@ -381,8 +381,17 @@
 			local_part = local_part.replace(" ", "_")
 		else:
 			local_part = self.get_random_ascii_string()
-		domain_part = self.get_primary_domain_from_disk()
-		new_email = "{}@{}".format(local_part, domain_part)
+
+		customer_domains = self.list_domains()
+		for domain in customer_domains:
+			if domain["domainName"] == domain_part:
+				# A valid domain was given, do not modify mail address
+				self.logger.debug("fix_email: valid found in email address %s" % email)
+				return email
+
+		# Domain not found in google account, modify given email to use primary domain part
+		primary_domain_part = self.get_primary_domain_from_disk()
+		new_email = "{}@{}".format(local_part, primary_domain_part)
 		if email != new_email:
 			self.logger.error("Email address %r invalid, changed to %r.", email, new_email)
 		return new_email