


How to Determine the Content-Type of Email Attachments in PHP?
Nov 21, 2024 am 11:08 AMDetermining File Content-Type for Email Attachments in PHP
In PHP, sending an email with file attachments requires specifying the content-type of the file. This information enables the email client to correctly interpret and display the attachment. This article addresses how to set the $the_content_type variable properly for this purpose.
Solution:
One approach involves using the getFileMimeType() function, which employs a series of fallbacks to handle different PHP versions and unreliable mime type functions:
function getFileMimeType($file) { // Try finfo_file if (function_exists('finfo_file')) { $finfo = finfo_open(FILEINFO_MIME_TYPE); $type = finfo_file($finfo, $file); finfo_close($finfo); } // Try mime_content_type else { require_once 'upgradephp/ext/mime.php'; $type = mime_content_type($file); } // Check for unreliable results if (!$type || in_array($type, array('application/octet-stream', 'text/plain'))) { // Try file command (only available on *NIX systems) $secondOpinion = exec('file -b --mime-type ' . escapeshellarg($file), $foo, $returnCode); if ($returnCode === 0 && $secondOpinion) { $type = $secondOpinion; } } // Try exif_imagetype for images if (!$type || in_array($type, array('application/octet-stream', 'text/plain'))) { require_once 'upgradephp/ext/mime.php'; $exifImageType = exif_imagetype($file); if ($exifImageType !== false) { $type = image_type_to_mime_type($exifImageType); } } return $type; }
This function sequentially tries the native finfo_file, mime_content_type, file command, and exif_imagetype functions to determine the content-type. If one of these methods returns a reliable result, it's used. Otherwise, the function returns a fallback content-type.
Once the content-type has been determined, you can set the $the_content_type variable as follows:
$the_content_type = getFileMimeType($filepath);
This approach provides a robust solution for determining the content-type of various file types in PHP, ensuring that your email attachments are displayed correctly by email clients.
The above is the detailed content of How to Determine the Content-Type of Email Attachments in PHP?. For more information, please follow other related articles on the PHP Chinese website!

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