I’ve made a few posts already about issues with emails being rejected by gmail addresses with a variety of messages. Ultimately, the solution that seems to have finally resolved my problems includes the following steps:
send a message from your email address to mail-tester.com and fix any issues that show up, this may involve setting the DKIM, DMARC, and SPF settings in your DNS settings. I found that cyberpanel creates the DKIM with quotation marks and for some reason removing those quotation marks worked better for me.
The final adjustment I made that seems to have fixed the issue (hopefully for real now) is making sure that in Cloudflare I make the IP address visible for the mail server A record. I also set-up an AAAA record for the mail subdomain to also point to the IPv6 address.
I was thinking there should be a way to configure things so that the IP address doesn’t have to be visible, but it makes sense that if they are verifying the IP address of the sending email and making sure it matches the reverse DNS setting – it would need to see the IP address.
I’ll see if this keeps the issue fixed, as previous solutions worked intermittently but I only found out after some time that they were not fully working.