We have a few webservers and our corporate mail is @ gmail. They don't allow relaying thought them, so I dont want to setup each server since there behind load balancers, etc. so I want a central mail server, an alias domain like ads.domain.com (as one part of the business has classifieds) so a lot of that mail is using local sendmail and going to spam since the sender doesn't match the server and the sent-from.

So, I think Im talking using a smarthost, but is there a nice how-to, as well as what server should be used, sendmail, postfix, etc.

I will setup the spf records and the domains that point to him, then all the servers will send mail which will be then routed though that one box.

Thats the what I want, looking for a nice how-to or at least suggestions on where to start.

Thanks

These days it is very hard for legitimate mail to avoid ending up in the spam box. If you want to ensure that most of your mail reaches people's inboxes you would do well to outsource emailing to a specialist email service provider.