http://www.postfix.org/ADDRESS_VERIFICATION_README.html
When I was attempting to register for the boards, my host which has implemented Postfix SAV would not accept your web form which had an invalid 'MAIL FROM' in the SMTP Envelope:
Dec 6 14:05:28 mx3 pf-in/smtpd[82014]: NOQUEUE: reject: RCPT from coppermine.vm.bytemark.co.uk[80.68.88.129]: 554 5.1.7 <www-data@coppermine.vm.bytemark.co.uk>: Sender address rejected: undeliverable address: host a.mx.coppermine.vm.bytemark.co.uk[80.68.88.129] said: 550 Unknown user (in reply to RCPT TO command); from=<www-data@coppermine.vm.bytemark.co.uk> to=<MY_EMAIL_ADDRESS> proto=ESMTP helo=<coppermine.vm.bytemark.co.uk>
Your verification email has the envelope (SMTP Session, not header) MAIL FROM of
from=<www-data@coppermine.vm.bytemark.co.uk>
However your MX server responds 550 Invalid user when attempting to validate that address.
I had to beg my ISP to whitelist your revdns (coppermine.vm.bytemark.co.uk[80.68.88.129]), but it would be much simpler if your MAIL FROM where a valid mailbox, even if you had it delivering to |>dev/null
You're right. Thanks for the report.
I will quote your message in a new thread on a dev-only board (http://forum.coppermine-gallery.net/index.php/topic,62774.0.html) and we'll try to come up with a solution. Thanks again.
Joachim