I have an existing email filtering program that currently uses Sendmail as the MTA. I want to move to using Postfix instead. The filtering program is implemented as an SMTP proxy. One of its features is to force a message to be re-routed if it finds certain things in the content of the message e.g. words within an attachment.
This currently works with Sendmail as follows: The filtering program adds an X-header defining the required next-hop address and port number Sendmail reacts to the X-header and overrides the normal routing behaviour I'm trying to find a way to make this work when integrated with Postfix instead of Sendmail. I can change the way the filtering program behaves if necessary. Rob -----Original Message----- From: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] On Behalf Of Wietse Venema Sent: 03 June 2016 15:32 To: Postfix users <postfix-users@postfix.org> Subject: Re: Can a content filter override the routing nexthop ? Rob Maidment: > Some confusion here, probably because I have used the wrong > terminology. When I said I have a content filter that needs to > influence how a message is routed, I meant a content filter that is > implemented as an SMTP proxy sitting between two Postfix instances. > > That said, Wietse's response led me to a solution I think: > > The SMTP proxy can add an X-header indicating where the message should > be routed. > In the upstream Postfix instance I can configure header_checks to > check for the X-header and return a FILTER response based on the > header value using a regex. > I'll need to take steps to ensure this can't be exploited, e.g. by > stripping the X-header if it exists in the downstream Postfix > instance, or in the SMTP proxy. What problem are you trying to solve? Please describe the problem, not the solution (adding a header that triggers a FILTER action). Wietse ---------------------------------------------------------------------------------------------- Message Processed by the Clearswift V4 Engineering Dogfood Secure Email Gateway This e-mail and any files transmitted with it are strictly confidential, may be privileged and are intended only for use by the addressee unless otherwise indicated. If you are not the intended recipient any use, dissemination, printing or copying is strictly prohibited and may be unlawful. If you have received this e-mail in error, please delete it immediately and contact the sender as soon as possible. Clearswift cannot be held liable for delays in receipt of an email or any errors in its content. Clearswift accepts no responsibility once an e-mail and any attachments leave us. Unless expressly stated, opinions in this message are those of the individual sender and not of Clearswift. This email message has been inspected by Clearswift for inappropriate content and security threats. To find out more about Clearswift’s solutions please visit www.clearswift.com
