Mark Goodge schrieb: > Dan Slay wrote: >> Thanks, that's what I have read. Which is why this make things more >> awkward. >> >> I cannot see that holding a recipient list is a solution. If, for >> instance, you relay for thousands of domains all going to different >> MTA's that hold each individual domains recipient list, its not really >> that straight forward and may impact performance? > > Postfix can generate and maintain an internal recipient list by means of > a recipient check on the downstream MTA before accepting mail to a > previously unknown user. See these pages for information on how it works: > > http://www.postfix.org/postconf.5.html#reject_unverified_recipient > http://www.postfix.org/ADDRESS_VERIFICATION_README.html#recipient > > Correctly configured, with the right degree of persistance in the cache, > this will have minimal impact on performance while also significantly > reducing backscatter. The actual tradeoff between effectiveness and > performance is dependent on how long data is cached for; if your system > can cope with it then it's best not to cache at all as that's the only > way to ensure zero backscatter. But even a fairly lengthy cache time > will be sufficient to prevent the majority of backscatter, provided that > the recipient email addresses don't get switched off very often. > > Mark
additional you may have problems with mail servers using greylisting during recipient verification, so normally you should only do this if you sure that no greylisting is done for your servers ip on the verification servers and they give a i.e 550 for not existing mail adresses as well your server should do so after verification result, therefor having a recipient list is the right way -- Best Regards MfG Robert Schetterer Germany/Munich/Bavaria
