Can't Receive emails

Hello,

I have just Installed new CWP control panel and I love it, it look amazing.

But I have issue that  have hosted my first domain and created email accounts.
I can see email accounts, I can send email but when I receive email it stuck in email Mail Queue
and when I click on View Button on email I got this error on top of email

Queue reason:
8A8178161AB2    5855 Mon May 22 00:10:50  *****@yahoo.com

(host 127.0.0.1[127.0.0.1] said: 451 4.6.0 id=216992-11 - Temporary MTA failure on relaying, from MTA(smtp:[127.0.0.1]:10025): 451 4.6.0 Alias expansion error (in reply to end of DATA command))
                                         **@**.net

I have also Pressed Process QUE button few times but noting emails are not delivering to its mailbox.

how to fix this.

Thanks

Try to rebuild postfix (main) config.

CWP --> MailServer Manager:

I recommend you to enable the followiong options (Don't check everything for testing purposes):

rDNS Check (recommended)
Install DKIM & SPF (recommended)

Make sure "Hostname" and "Domain" have correct values.

Click "Rebuild Mail Server", wait some time and then try to send/receive emails again.

And open all mail-related ports in the CSF firewall:
143,993,110,995,25,465,587