iCloud Email

See - https://support.apple.com/en-us/HT203528

isangy1025 Said:

"iCloud Email: Hi! So I haven't been recieving any emails on my iCloud. If a company tells me they sent me an email, I don't get it."

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Try the Following...

• View the filters you have set up.
• Try having then send it to another eMail account.
• Check another device, and see if it was received on that device.
• Receiving the eMail is not always instantaneous to it being sent.
• Ask them to eMail someone else with an iCloud eMail (with the recipient's approval).
• If it does not go through, then maybe they are having issues with it getting out of their own server.