All 7 Email Sending in PHP (PHPMailer & SMTP) questions
More in Email Sending in PHP (PHPMailer & SMTP)
How does PHP's built in mail function work, and why is it generally not recommended for production applications? What is PHPMailer, and what advantages does it provide over PHP's built in mail function for sending emails reliably? What is SMTP authentication, and why is properly configuring it important for ensuring email deliverability? How do you send an HTML formatted email with an embedded image or attachment using PHPMailer? How should an application handle email sending failures gracefully, and why is sending emails asynchronously through a queue often preferred over sending them directly during a web request? What security considerations should be addressed when building an application feature that sends emails based on user input, such as a contact form or password reset flow?
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PHP › Email Sending in PHP (PHPMailer & SMTP)

How do SPF, DKIM, and DMARC email authentication records help improve email deliverability and prevent your domain from being used for email spoofing?

Intermediate

Answer

SPF, or Sender Policy Framework, specifies which mail servers are authorized to send email on behalf of your domain, DKIM, or DomainKeys Identified Mail, adds a cryptographic signature to outgoing emails that receiving servers can verify to confirm the email was not altered in transit, and DMARC builds on both of these by telling receiving mail servers exactly how to handle emails that fail these checks, together significantly improving the trustworthiness and deliverability of email sent from your domain.
; Example SPF DNS record
example.com. TXT "v=spf1 include:_spf.google.com ~all"
Real-world example A company setting up transactional emails for its application configures proper SPF, DKIM, and DMARC records for its sending domain, resulting in a noticeable improvement in email deliverability rates to major providers like Gmail and Outlook.

Common follow-ups: How do you verify that your domain's SPF and DKIM records are configured correctly?;What happens to an email that fails SPF or DKIM verification under a strict DMARC policy?

Security;Deployment & Hosting for PHP Applications
All 7 Email Sending in PHP (PHPMailer & SMTP) questions