I've registered a domain in a domain registrar, and in one of its' upgrades it includes an email address for the domain (for example
email@example.com if I registered the domain
example.com), for a monthly fee.
However, even without upgrading to that plan, the registrar includes the option to forward emails to my personal email address.
For example, every email sent to
firstname.lastname@example.org will be received in my own personal
email@example.com inbox. It automatically appends the appropriate MX records to the DNS table for the domain.
How is that possible, if I haven't created the mail address for
What makes it able to receive and forward emails, but not send ones from that address (or maybe there is a way to do that, and the email address upgrade includes different perks)?