Email bounced with error 554 5.7.1 Recipient address rejected: NO-DOMAIN
Somebody tried to send me an email and said that he got this error back.
554 5.7.1 Recipient address rejected: NO-DOMAIN
The sender is using a custom domain, from the DNS it looks like it's hosted by Google. My own domain is from Namecheap, I've had it for years and it's not expiring until July.
Is this a problem on his side or mine? I never had any issues before (at least I hope I didn't). I didn't do any changes to my DNS recently.