Email forwards are bouncing back

Email forwards are bouncing back

Hello!

I set up an email address (not the one connected to the Zoho client-let's call it Email 1) to forward to an email connected to the Zoho client (Email 2). It was working for a while but apparently in the past few months it has stopped working.

The emails from Email 1 do not forward to Email 2- instead the Email 1 client receives the following message:

"SMTP error from remote server for RCPT TO command, host: mx.zoho.com (204.141.32.121) reason: 541 5.4.1 Mail rejected by destination domain"

The same message appears in the spam folder for Email 2.

I can't figure it out! I made no changes to either mail setting. I did just add Email 1 to the whitelist just in case but that didn't work

T