Solution
PTR record test and spam email validation
Recently I faced issue sending emails to Gmail servers using my Cyberpanel. I have been getting error similar to below: host gmail-smtp-in.l.google.com[2x04:xxxx:xxxx:c1x::xb] said: 550-5.7.25 [xx01:xx80:xxxxx:xxxxx:xxxx:4ff:xx58:xx68] The IP address sending this 550-5.7.25