"Some sites may blacklist you when you are probing them too often (a probe is an SMTP session that does not deliver mail), or when you are probing them too often for a non-existent address. This is one reason why you should use sender address verification sparingly, if at all, when your site receives lots of email."
http://www.postfix.org/ADDRESS_VERIFICATION_README.html#limitations As our user may do mailings from time to time, i do not want to get bad reputation by probing microsoft,yahoo whatever too often. :) for remote site, i see no difference between sender and recipient verification. in both cases, im doing a 'half delivery' of a mail. Am Mittwoch, 16. Januar 2019 schrieb Viktor Dukhovni < postfix-us...@dukhovni.org>: >> On Jan 16, 2019, at 9:56 AM, Wietse Venema <wie...@porcupine.org> wrote: >> >>> reject_unverified_recipient is no option as remote sites don't like >>> probing/verify requests. After rechecking, i had a typo in my regex. >> >> reject_unverified RECIPIENT, not reject_unverified_SENDER > > Specifically, because it would be used on the submission port or > only for clients in trusted networks, it would not be open to abuse > by random strangers. The same users allowed to send email to the > remote site, are the ones who would initially trigger a verification > probe occasionally as part of submitting an outbound message. > > It is fairly safe, and should not raise any issue with remote > receiving systems. You can monitor your logs for signs of > misuse by trusted clients. > > -- > Viktor. > >
