my iCloud mail does not receive any emails from other sender (not apple)

Hello,

I am experiencing a serious issue with my iCloud Mail account.

I can receive emails sent by Apple (for example, security notifications, sign-in alerts, and storage notifications), but I do not receive any emails from other senders.

I tested this by sending an email from my Gmail account to my iCloud email address. Gmail shows that the message was sent successfully, and there is no delivery failure or bounce-back notification. However, the email never appears in my iCloud inbox.

I have also checked my mailbox through the iCloud website, not just on my iPhone, and the message is still missing. I checked the Spam and Trash folders as well, but the email is nowhere to be found.

Because of this issue, I cannot receive verification emails, password reset emails, or any other messages from websites or services that I register for.

So far, only emails sent directly by Apple are being delivered to my iCloud mailbox.

Could you please help me determine why my iCloud Mail account is not receiving emails from external senders and how I can fix this issue?

Thank you.