I sent an email to Paypal, and it was bounced with the various headers
shown below (let's not get too bogged down with the difference between
Paypal and Ebay).
The critical part of the bounce message is (after unscrambling the Q-P
and rewrapping):
5.1.0 - Unknown address error 550-'
5.7.1 Service unavailable; \
Client host [66.135.195.180] blocked using
list.dsbl.org; \
http://dsbl.org/listing?66.135.195.180'
which is odd, because the original message dpes not appear to have passed
anywhere near that IP, although as you will see the bounce came via it.
The original message was sent to
email.paypal.co.uk, whose MX points to
email-mx.paypal.com whose A record is 206.165.245.161, for which there is
no reverse DNS. The message passed via
v-smtp-auth-relay-2.gradwell.net
(which is my provider's smarthost), and was next seen at
sjciport01.sjc.ebay.com, which cannot be resolved at all within the DNS,
even by ebay's nameservers. Moreover, you will observe that there are two
Received headers, one second apart, purporting to show that
sjciport01.sjc.ebay.com got it from
v-smtp-auth-relay-2.gradwell.net.
