i'm using a Debian 9 with Postfix and i've got issues with my mails sending to google mail.
After sending a mail, i will instantly get a response: "Undelivered Mail Returned to Sender".
Our System has detected that this message is 550-5.7.1 likely suspicious due to the very low reputation of the sending IP 550-5.7.1 address. To best protect our users from spam, the mssage has been 550-5.7.1 blocked.
My score on mail-tester.com is 10/10 (the only warning stated is a missing unsubscribe link).
I've added an SPF-Record, a DKIM Signature and DMARC-Record. A reverse DNS entry is also added.
I've looked up several blacklist and all stated that i'm good to go.
I was wondering if the issue would solve itself after some time. The Mailserver was setup ~three weeks ago and after two weeks, mails were accepted from gmail for a few hours (going in gmails junk-folder, but at least no bounce). A bit later they were getting bounced again.
Google Postmaster-Tools doesnt show anything due to low message amount (as those are just private mail accounts, no bulk/newsletter mails).
Is there anything else I could have missed?
Thanks for your time!
