Email Rejected By Server
I began receiving the error message: “Cannot send mail. A copy has been placed in your outbox. (Recipient) has been rejected by the server.” I deleted all of my email accounts and added them again. I sent a test email to someone and it worked. About an hour or so later, I tried to send an email, and the message popped up again. I am running iOS 11.2.1. I am using an iPad Pro. I am also running the same version on my iPhone 8 Plus, and it seems to be working fine.
iPad Pro Wi-Fi, iOS 11.2.1