I had this issue as well. Mostly ive used namecheaps forwarding plus googles smtp to send. Because i lose forwarding when i change to cloudflare as dns, i creat

I had this issue as well. Mostly ive used namecheaps forwarding plus googles smtp to send. Because i lose forwarding when i change to cloudflare as dns, i created this: https://ForwardMX.io https://ForwardMX.io Most of my domains just receive. For these that need send i setup a alias in Gmail and use Googles SMTP (as mentioned)