I'm re-implementing an overloaded Postfix cluster, which beyond its many problems, has major efficiency concerns. The cluster is a dedicated MX Gateway, so mailboxes are not a consideration. Efficiency really is a significant concern, as we handle a substantial amount of mail, and the cluster is on its knees. I/O isn't our bottleneck, and statistics have confirmed this conclusion.
Currently I'm considering how attachments are processed, and weighing the methods. I assume once I know the proper method, I could locate the feature specific projects.
I've still got a few questions, even after reading the Postfix docs.
Postfix Milters: Are they only available before-queue? The docs mention some limitations, are Postfix Milters able to do things like strip certain attachments from an email? What about scanning for viruses, and removing them as well?
Before-queue Content Filters, and After-Queue Content Filters: The docs also reference using an SMTP proxy, to an internal address, is that just a specific method to utilize Content Filters? Would an alternate method use something like an external program/script? But both would be different ways to setup Content Filers?
Which is more appropriate for virus scanning, and stripping infected files? Same question for stripping banned attachment types? What about spam detection methods, such as DCC? With performance/efficiency being a significant concern, which method is most ideal? The docs describe all the methods horrifically!
I really appreciate any expert suggestions!