How to set up domain authentication
This information was provided by sendgrid because some text reminders are not being received by patients using specific carriers.
From SendGrid Domain authentication, formally known as domain whitelabel, shows email providers that SendGrid has your permission to send emails on your behalf. To give SendGrid permission, you point DNS entries from your DNS provider (like GoDaddy, Rackspace, or Cloudflare) to SendGrid. Your recipients will no longer see the “via sendgrid.net” message on your emails.
Email service providers distrust messages that don't have domain authentication set up because they can not be sure that the message comes from you. Explicitly stating that it comes from you increases your reputation with email service providers which makes it much less likely that they will filter your mail and not allow it get to your recipient's inbox, which increases your deliverability. You are also explicitly showing your recipients that this email comes from you, so they are less likely to mark your mail as spam. This will help you build a positive reputation and this proper authentication may help bypass this 550 error. For some additional information on domain authentication and how to set it up, please see some of our documentation below: