some Users are unable to send E-mails to us.
They are getting
Remote Server returned '554 5.0.0 <utm.acme.at #5.0.0 smtp; 550 Error: open resolver; https://www.spamhaus.org/returnc/pub/18.104.22.168>'
if I klick on the Link Spamhaus tells me that the Problem is on the receiving side.
I do'nt know where the IP is from.
I've read the Spamhaus Page but can't figure out what's wrong.
The Count of Emails getting blocked are rising every day and i have to solve the problem.
I've googled the problem but there are no evidences :-(
would be lucky if someone could help
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