Freelancers do NOT have @sky.com e-mail addresses.
Freelancers are self-employed.
Staff are employed by the company.
You can’t be a staff freelancer. It’s not possible to be both. It’s an either/or situation.
Hence, if you send an e-mail and the address does not exist then the postmaster should return it to you. If you send an e-mail but receive no reply then there is some other reason for that, but you’ll have to live with it.