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.