no, the phpmailier would not be able to be used as a substitute.
That script would require changing the forms action, which would break the insert record behavior on the registration page.
It also would not be able to send the verification link in the email.
About the only option other than finding an SMTP server that would allow you to use it without authentication would be using Universal Email to edit the email behaviors in the user registration solution pack to use the Pear Mail For SMTP mail object, the Pear mail object allows for authentication to be passed.
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