Re: Accept external SMTP traffic only from MX hosts

It sounds as if you want something like SPF and a policy daemon. Just google it.

Re: postfix after queue content filter

It seems that the local delivery (pickup?) uses the content filter which it shouldn't, AFAIK. If that is the case, the following master.cf configuration taken from my installation may help: -- snip --- :smtpinet n - n - - smtpd -o content_filter=