Alexandre Ellert: > Hi, > > I relay transactional mail for my customer's web sites. > Each website has it's own SASL authenticated account and mail are > sent via submission or smtps. > > But, some website doesn't verify email existence when a user submit > a web form or 'create an account'. > That's why I often see my postfix relay trying to send to non-existing > email. > Sending again and again to non-existing mail can lowering my IP > reputation and waste ressources that's why I need a solution.
You can push the problem back to the webservers, by using the the Postfix SMTP server's "reject_unverified_recipient" feature. With this, Postfix will make one connection for the recipient address, and then the Postfix SMTP server answers with 5XX to the web application when that recipient does not exist. There are no repeated connections, because Postfix stores the results in a cache (both positive and negative). For details: http://www.postfix.org/ADDRESS_VERIFICATION_README.html You'll have to adjust some settings so that Postfix replies with 5xx (by default it replies with 4xx to be on the safe side). Wietse
