How can PHP developers handle special characters, such as umlauts, in email headers to avoid "Bad Header" warnings?

Special characters, such as umlauts, in email headers can cause "Bad Header" warnings due to encoding issues. To handle this, PHP developers can use the `mb_encode_mimeheader()` function to properly encode the special characters before setting the email headers. 

// Set the email subject with special characters properly encoded
$subject = 'Subject with ümläuts';
$encoded_subject = mb_encode_mimeheader($subject, 'UTF-8');

// Set the email headers with the encoded subject
$headers = "From: sender@example.com\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=UTF-8\r\n";
$headers .= "Subject: $encoded_subject\r\n";

// Send the email
mail('recipient@example.com', 'Subject with umlauts', 'Email body content', $headers);

Keywords

PHP special characters umlauts email headers Bad Header warnings

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