unabe to send emai to myself

unabe to send emai to myself

Dear Zoho Team,

I have a co.uk domain and using ZOHO mail free version. one problem is that I can't send email to myself.
my email is support#vampal.co.uk.
when I use the ZOHO web client and send an email to myself, I got an error as below:

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.
Invalid Address, ERROR_CODE :550, ERROR_CODE :5.7.1 Unable to relay for support#vampal.co.uk.

however, I can send email to others and also I can get their emails except myself.
according to this I believe my MX record is correct.
this doesn't happen on my friend's email. he has a .com domain and also using ZOHO free version,
he can send himself emails in the web client.

And, I test some free email services like Google, outlook, they can both support sending email to yourself.

is this a problem or a bug?

thanks very much!


Regards
Synn