Hi
According to NZZ we are rejecting all emails with sender domain @bounce.email.nzz.ch with "Receiving email server is temporarily overwhelmed with delivery attempts, from you and other senders". Unfortunately their feedback is very vague, no logs or exact times of issue from their side.
I can't find any such emails in our log, but I see some are SRS forwarded from bluewin, VTX, Hostpoint etc. and do reach us. Unfortunately I have no access (without customer permission) to the content and therefore can not glimpse at the email headers to find the true origin.
Could somebody do me a favour: From which IP Address do you see emails with envelope domain @bounce.email.nzz.ch being delivered?
It used to be salesforce: 13.111.14.63 until 17. August, but I fear this changed, which causes the issue, as I have seen at least one email delivered with this domain, failing SPF from an IP belonging to Liberty Global Austria if this was not some broken forwarding attempt.