diff --git mail/univention-mail-postfix/conffiles/etc/postfix/main.cf.d/30_maps mail/univention-mail-postfix/conffiles/etc/postfix/main.cf.d/30_maps
index df2ec53d81..a071b83c15 100644
--- mail/univention-mail-postfix/conffiles/etc/postfix/main.cf.d/30_maps
+++ mail/univention-mail-postfix/conffiles/etc/postfix/main.cf.d/30_maps
@@ -34,8 +34,9 @@ print('')
 # enable virtual tables if requested
 if configRegistry.is_true('mail/postfix/virtual/enabled', False):
 
-	default_virtual_alias_maps = 'hash:/etc/postfix/virtual, ldap:/etc/postfix/ldap.groups, ldap:/etc/postfix/ldap.distlist, ldap:/etc/postfix/ldap.virtual, ldap:/etc/postfix/ldap.external_aliases, ldap:/etc/postfix/ldap.sharedfolderremote, ldap:/etc/postfix/ldap.sharedfolderlocal_aliases, ldap:/etc/postfix/ldap.virtual_mailbox, ldap:/etc/postfix/ldap.sharedfolderlocal'
 	default_virtual_mailbox_maps = 'ldap:/etc/postfix/ldap.virtual_mailbox, ldap:/etc/postfix/ldap.sharedfolderlocal'
+	# Bug #45205: adding mailbox_maps to alias_maps, so both will be together in the unionmap below
+	default_virtual_alias_maps = 'hash:/etc/postfix/virtual, ldap:/etc/postfix/ldap.groups, ldap:/etc/postfix/ldap.distlist, ldap:/etc/postfix/ldap.virtual, ldap:/etc/postfix/ldap.external_aliases, ldap:/etc/postfix/ldap.sharedfolderremote, ldap:/etc/postfix/ldap.sharedfolderlocal_aliases, {}'.format(default_virtual_mailbox_maps)
 	default_virtual_domains = 'ldap:/etc/postfix/ldap.virtualdomains'
 
 	virtual_alias_domains = re.split(',\s*', configRegistry.get('mail/postfix/virtual/alias/domains', '' ))