Can anybody confirm this would work ?
I have two MX-configured DNS records to handle smtp and pop. I'd like to implement a 'mailing list' server in another machine so:
Would it do any harm the fact that this third mail server has no user inboxes ?
Would the mails that it sent be acknowledged as valid by the receiving servers given it's ip/name is present as a MX record ?
You need Sender Policy Framework. The purpose of Sender Policy Framework (SPF) Text is to allow a mail server to validate that the sending mail server is authorized to send mail on behalf of a domain. Having an SPF record can reduce email fraud and forged email. There used to be an SPF Setup Wizard to generate a string. But it seams to be off line right now. It might work again by the time you get to it, so here it is. http://openspf.org
take a look at domain keys for this: http://en.wikipedia.org/wiki/DomainKeys Your idea has major issue if your main mail servers are down, then all incoming mail would flow to 'mailing-list' server. In sendmail, we generally do masquerading domain and it works just fine.