How to implement something close to, but not quite an "announcement-only" mailing list?

[Ramon F Herrera]

The spam bombardment is getting out of hand. With this project, we are trying to defend ourselves from the onslaught.  I have implemented this in the past, from scratch, but don't have the time now. The goal is to implement a mailing list with the following requirements:  (1) As usual, mail sent to mygr...@somecompany.com will be distributed to the participants, but only messages from senders in the list of approved people will have their messages accepted and forwarded. The set of participants is almost identical BUT not necessarily the same as the set of authorized users. Some people call this an "announcement only" mailing list.  (2) The verification of the sender will be done in the harder to fake Unix "From_" header as opposed to "From:".  (3) Any e-mails addresses contained in the headers ("From:", "To:", "Cc:", etc.) will be disguised and the real name of the person will be used.   Let's say that an e-mail arrives with this header:   From bga...@microsoft.com   [...] more headers   From: William Gates, the 3rd. <bga...@microsoft.com> That header should be rewritten to either:    From: William Gates, the 3rd.    or, if that particular syntax is not allowed, we could add some non-operational address as follows, something similar to <do-not-re...@xyz.com>    From: William Gates, the 3rd. <address-disgui...@somecompany.com> For added security/performance, I would code this as a sendmail/postfix filter, written in C. In fact, the mailing list to which I am sending this is very close to my needs, except that may e-mail remains visible. Perhaps Majordomo is the answer? I barely know its capabilities, though. TIA, -Raymond