Can send but not receive emails

Can send but not receive emails

So I decided to choose Zoho for my business email, and I love it, all apart from one problem. I can send emails from my business account ( alex@exosites.co.uk), but it's just refusing to receive them. I've checked over and over again and everything's set up right. Before a load of staff come on going 'Check your MX'. Please, telling me to check my MX isn't helpful because I have done so numerous times. Anyway, thanks in advance.

-Alex