What is the purpose of using RegEx for modifying email headers in PHP?

When modifying email headers in PHP, Regular Expressions (RegEx) can be used to search for specific patterns within the headers and make necessary modifications. This can be useful for tasks such as adding custom headers, changing existing headers, or filtering out unwanted headers. 

// Example of using RegEx to modify email headers in PHP

// Original email headers
$headers = "From: sender@example.com\r\n";
$headers .= "Reply-To: replyto@example.com\r\n";
$headers .= "X-Mailer: PHP/" . phpversion();

// Use RegEx to add a custom header
$headers = preg_replace('/(From: )/', '$1CustomHeader: customvalue\r\n', $headers);

// Output modified headers
echo $headers;

Keywords

RegEx email headers PHP modification purpose

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