Perch not sending email

Hi again,

After moving a client site live I'm having trouble with email on the server. If the config file has an email address of me@myaddress.co.uk it sends successfully, however if I change the config file to the client's address e.g info@client-domain.co.uk and do a test it errors with

"could not instantiate mail function"

I realise that there maybe requirement for the client to speak to their hosting provider, but why would it work with my address and not another address?

Also does the email address in the config take precedent over the send from address in a Perch form options or is just for testing?

Many thanks

Lee Many thanks