I've been trying to set up my two zoho mail accounts on my phone but am having the following Undelivered error message:-

 INVALID_ADDRESS, ERROR_CODE :553, ERROR_CODE :Relaying disallowed 

It was previously working but I was unable to send emails from my phone, so I tried to re-set up and now am worried I wont be able to receive anything from external accounts on desktop or phone.

Please help,

Becky