Using static IP or certificates to send e-mail from automated tests without requiring a special userid

Using static IP or certificates to send e-mail from automated tests without requiring a special userid

Our business has a static IP. We run automated regression tests that send results by e-mail to our users. Is there any way to whitelist our IP address with Zoho so that all e-mails sent from our IP are delivered by Zoho without needing a separate userid to be setup. Alternatively, is there a way to validate using certificates rather a userid? Thanks.