I have an issue with emails from multiple accounts being sent to SPAM by gmail and others. It's a real problem because they are quotes for work which we are missing out on. I have checked the IP for blacklisting and all is fine, except for this at DNSBL Check:
This IP was flagged due to misconfiguration of the e-mail service or the suspicion that there is no MTA at it.
When requesting a delist key, I get this:
Delist key can not be sent due to denial of destination server:
Invalid Addresses
Please consult your MX administrator to resolve this issue.
I don't have time to spend on this.