Apple blocked emails...

When an email is blocked what does the sender receive from me? Apple? A friend received an email indicating I had blocked her at iCloud.com. See copy of message below. Did not open anything.

From: Mail Delivery Subsystem <mailer-****@ googlemail.com>

Date: March 11, 2020 at 10:49:15 AM EDT

To: ****@ gmail.com

Subject: Delivery Status Notification (Failure)

Message blocked

Your message to ****@ icloud.com has been blocked. See technical details below for more information.LEARN MORE

This link will take you to a third-party siteThe response from the remote server was:

550 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137

[Edited by Moderator]