I have ISPConfig 3.1.15p2 running under Ubuntu 18.04 with rspamd and I have one domain on another server (a shared hosting with a terrible mail antivirus). Is possible to set ISPconfig as a mail gateway in order to get mail destined to external domain, check for virus and, if it is clean, deliver it to domain on external server? I tried with mail routing but mail is not delivered and I receive this error: This is what I tried: Email -> Global filters -> Relay recipients: set @externaldomain.com as relay recipient. I tried with [email protected] too but doesn't work either. Email -> Email accounts -> Email routing: Domain: externaldomain.com type: SMTP No MX lookup checked Destination: external server IP I'm not sure if relay repicient and mail routing domain should be externaldomain.com, @externaldomain.com or *@externaldomain.com (in ISPConfig manual examples relay recipient has @ but not in mail routing domain. Am I missing something? Should I create externaldomain.com mails on Ispconfig server? Can I use ISPConfig server as mail antivirus gateway? Thanks.