Emails sent to iCloud email are undeliverable
The emails I sent from my official emails to my private iCloud email remains undeliverable.
I’m unclear what sort of mail setup is being used here. Are you using your own domain and hosting, for instance? Or some mail provider, such as Gmail or Proton or Apple iCloud (without your own domain involved)?
That error usually means the sending email server is misconfigured, or the local mail app setup is using the wrong SMTP server for the email account.
Is your sending email server configured correctly, including SPF, DKIM, etc?
Does removing and re-adding the email account in the mail app resolve this?