I have a long-running problem concerning one email address which is always rejected by Gmail when forwarded from my domain. The issue has gone back and forth like a ping pong ball between me and my domain registration company, and I am getting nowhere. The email address is from a highly respectable business and there is definitely no question of spam being involved. Other people from the same business are able to email me without issue using their company domain as does the one address which is being blocked - from the most senior person in the business ! The email address does not appear on any blacklists and I have whitelisted it in my Gmail account. But it makes no difference. I get the same result “ Gmail does not designate 220.127.116.11 as a permitted sender ”.
The only question I have not yet asked anyone is whether this could have anything to do with Cloudfare and my domain’s security certificate ? I cannot imagine that it does, but I thought it best to ask the question.
Can anyone advise ? For instance, is there a Cloudfare whitelist just in case it is related to the issue ?