Blocking system of mailing 3

Today I received the message as follows.
The issue is that email address was blacklisted on 2019/10/24, it does not appear to be blacklisted anymore. Please have her try again.

So I told her to try again. But I'm afraid her email was still blacklisted and didn't work.
I send two return mail from FTH to her as attachments.
Please show me the solution.

The whole domain @163.com has been blacklisted

Go to Email & Contact Forms / Email Security
In the Crowd Sourced Blacklist section, put her full email address in the Exceptions box. That way your club will still use the crowd sourced blacklisting, but her address will be okay for your club.

Where do we find "Email & Contact Forms / Email Security"
Which website? Which webpage? On my club page there is nothing that matches the above.

Ron Fitch
President Alameda Tongue Twisters

In the admin section