Help with an issue

Hi all hope I can find some help with an issue that's driving me nuts.

So the website I'm working on has an odd issue.

Issue 1
When a customer places an order woocommerce generally sends a "new order received" email to the admin.

What I'm experiencing now is the mail only comes through to @gmail accounts. But if I set it to come to an email ending in the same domain as the website it doesn't send.

Issue 2
is that we use pay fast for payments.
Problem here is that when using pay fast the new order mail doesn't send even to Gmail accounts. But using direct bank transfer sends the "new order" email.

Any ideas will be appreciated