We're starting to see hosts on the internet block mail from our mailserver based on entries in the SMTP header's Received: fields on the grounds that certain outbound IPs have sent infected messages to the internet at some point in time.
The problem is that we have a large number of mobile contractors, and they're often on someone else's network, and that person's network shows up as a Received: entry. And sometimes that IP's presence in the list of Received: headers is enough to get a message blocked.
I can get around this by having our contractors establish a VPN connection, but that will get expensive quickly. I can also have debates with other mail server admins handling these devices, but that takes days to resolve.
What I would like to do is have Postfix strip out Received headers. I've found instructions to do this, but I'd like to know if anyone else has done this and if it's "safe" to do with Zimbra's Postfix.