Don't Use PHP Function mail() Print

Don't Use PHP Function mail()

The mail() function in PHP might seem like a quick and easy way to send emails, but it's riddled with security and reliability pitfalls. Here's why it's considered insecure—and what you should use instead.

???? Why mail() Is Insecure

• ???? Header Injection Vulnerability
  If user input is passed directly into the To, Subject, or especially the headers parameter, attackers can inject additional headers (like CC, BCC, or even custom SMTP commands) using newline characters (\r\n). This can be exploited to send spam or spoof emails.
• ????️ Lack of Authentication
  mail() doesn’t support SMTP authentication out of the box. That means you can’t securely send emails through services like Gmail, SendGrid, or Amazon SES without extra configuration.
• ???? Poor Deliverability
  Emails sent via mail() often lack proper headers (like DKIM, SPF, and DMARC), making them more likely to be flagged as spam or rejected by modern mail servers.
• ???? Remote Code Execution Risk
  The fifth parameter ($additional_parameters) can be abused to pass flags to the underlying mail transfer agent (like sendmail). If not sanitized, this can lead to command injection and even remote code execution.
• ???? No Built-in Validation or Error Handling
  mail() provides no feedback on whether the email was actually delivered. It only returns true if the message was handed off to the mail server—success is not guaranteed.

✅ Safer Alternatives

???? Pro Tip

If you're running large mailing lists such as used for marketing campaigns, using Mailman is often the most secure and scalable route.