Hello Together Question for mail infrastructure operators:
In the last weeks we had requests from customers, whose "newsletter" via sendinblue could not be delivered to us. In the logs I see at the given time, that the IP of sendinblue was on the blacklist of spamcop.net. That is, the mails were rejected by us.
The customer now says the mails go through everywhere else (I'm looking at you bluewin.ch), just not with you.
sendinblue suggests to whitelist their IPs (> 100'000 ip addresses) (https://help.sendinblue.com/hc/de/articles/208848409-SendinBlue-IP-Bereiche) Of course I would like to avoid this.
Question: How do other providers deal with such senders? Let everything from sendinblue through for the sake of the customers?
Thanks for your answers.
-- Michael Koloff sasag Kabelkommunikation AG