TOPIC: Confirmation emails not being sent

Good morning

We have tested DT Register thoroughly using PayPal Sandbox and confirmation emails are sent as expected.

However, having put the system live last night using PayPal as the payment gateway, it appears that most confirmation emails are not being received.

I have tried live tests using a few of email addresses that have no spam filtering etc. and some receive the email, some do not - it is clearly not being sent.

As soon as I put the system back into test mode with a Sandbox account all works fine.

Any ideas please?