Terry L. Inzauro wrote, at 06/15/2009 01:52 PM: > I like the idea of verifying addresses, but this stuck out. > > <snip from the "Postfix Address Verification Howto"> > > WARNING > > The sender/recipient address verification feature described in this document > is suitable only for low-traffic sites. It > performs poorly under high load; excessive sender address verification > activity may even cause your site to be blacklisted by > some providers. See the "Limitations" section below for details. > > </snip> > > what does the author consider as being low traffic?
As long as you follow Noel's advice and don't accidentally the whole Internet, you'll be fine. :) Furthermore, you may want to configure the optional persistent verification database and tweak the settings as needed to reduce excessive probes to the domain: http://www.postfix.org/ADDRESS_VERIFICATION_README.html#caching http://www.postfix.org/verify.8.html Keep in mind that this approach (recipient address verification) is better suited for gateways and is a somewhat imperfect match for a backup MX. If the primary goes offline, there is still a risk that your backup server will reject legitimate addresses that are not present in the cache. Nonetheless, it is better than becoming a backscatter source (though a real dump of valid recipients is far preferable).
