Cannot add users to Mail / unable to connect to messaging servier

Cannot add users to Mail / unable to connect to messaging servier

Hi,

I just signed up our business for Zoho Mail following a recommendation from a client.

However having verified the domain and changed MX records, which both worked well and fast. I am now not able to add users.

For the last hour I keep getting the message "unable to connect to messaging server, try again now".

What is wrong? Anything I am not doing right?

Help is highly appreciated.
Thanks.