Some Emails For Customers Are Not Being Sent


So I have a problem with email notifications.

Customers are not receiving email notifications regarding their orders and profile updates, but are receiving emails when a vendor replies to them in message center. (so emails in general are working, but the error is specific to the 2 cases mentioned above).

I am sure that I have the notifications enabled for customers from notifications settings; Also, the vendor and admin emails are receiving emails when an order is created/status change. However, only the customer is not receiving emails regarding orders.

Any thoughts on how to debug/the problem?