An email may not be able to be sent if the email address you are
sending the email to does not exist. If the email address does
exist, you may not have internet to be able to send the email, or
the email address may not be spelled right.
Not exactly. An email address can be compared to your home
address, only the email address is online. An email can be compared
to a letter. Like a letter is sent to your physical address, an
email is sent to your email address.