Pinging the SMTP server behind an email (sending a cheap ICMP) allows to easily check for invalid email providers without having to rely on sending the verification email as a proof.
Other options:
Allowlist of email providers
Sending the email regardless of availability of the service
Nice suggestion! Currently I have no feedback on whether or not the sent email was a success. It tells me "email sent!" but I check and the email didn't actually exist.
Pinging the SMTP server behind an email (sending a cheap ICMP) allows to easily check for invalid email providers without having to rely on sending the verification email as a proof.
Other options: