If you could enlighten us about the actual problem, we could give it a try?
If you could enlighten us about the actual problem, we could give it a try?

john.doe@example.com) is forwarding that john.doe@example.com to e.g. a @gmail.com or @outlook.com/@hotmail.com address, and that either Google or Microsoft is refusing to accept the message through Cloudflare.@example.com can then go in to Cloudflare like that, and search based on the message id, as seen from the end of the "521 5.3.0 Upstream error", to find out why the final destination rejected the message from Cloudflare.

@google.com, Cloudflare will reject the messages unless you're able to satisfy the requirements for DMARC ( e.g. (DKIM pass + domain alignment) || (SPF pass + domain alignment) ), but that is only because Google has set the reject policy.*test* instead of <strong>test</strong> but can't find what's doing that on my end550 5.1.1 Address does not exist. lER037lOKGee, but my custom address works

john.doe@example.comjohn.doe@example.com@gmail.com@outlook.com@hotmail.com@example.com{
"message": [
"Error: destination address not verified"
],
"level": "log",
"timestamp": 1701156019743
}@google.com*test*<strong>test</strong>550 5.1.1 Address does not exist. lER037lOKGeevar foo = { async email() {} }; export default a;export default { async email() {} }