I found this howto: https://www.howtoforge.com/the-perfect-spamsnake-ubuntu-jeos-12.04-lts-precise-pangolin which is using an older Version of Ubuntu but as the howto has absolutely no date and not even the comments have a date I have no idea how old that tutorial is and if there might be a newer one. My first question is if one can use one email gateway to filter incoming emails for SPAM and viruses with all bells and whistles like this tutorial seems to do for MULTIPLE MTAs. So what I mean is, can I have one Email Gateway filtering incoming emails then forwarding the emails for different domains to different servers? Say I have multiple small VPS machines which cannot run their own mail filtering due to resource limitations so I'd like to have one gateway handle incoming mails for them while they will continue to work as outgoing mail servers but only accept incoming emails from the gateway? I've also found this script: https://github.com/StrobeTechnologiesLtd/SpamSnake-Install which uses the same old Ubuntu version but seems to have been updated regularly. Another options seems this one: http://www.thockar.com/assp-home/ but it looks like this gets installed on each mail server aka not a gateway? Additionally I found mailscanner and scrollout (scrollout specifically mentions it can protect multiple domains and servers) Any other links for me to read up on?