I am an iCloud email service user since using the iPhone 3GS, or around 2009-2010. However, in the past year I have received a lot of complaints from friends who send me an email that every email they send always has a reply error. I don't really care about this, as long as the email stays in my inbox. I always say, "Enter the email".
But a few days ago after I migrated another email to Gmail servers, I casually tried to send an email to my iCloud email address. And it turns out that the reply error always appears like this:
It says the error status is "Illegal host / domain name found" on the domain dopushmail. So, in the default setting, every incoming email will be forwarded to dopushmail.com, which may be used for notifications. And if we are googling, many are having the same problem as me.
And the solution is very easy, I just need to uncheck the settings "ForwardingOn the menu General (see image below).
To enter the menu above, log into iCloud via a web browser, and then click the icon Setting in the bottom left of the browser, then select Preferences (see image below).
If so, you have the settings as above, please try again sending a message to your iCloud email, and the reply error will not appear again :)