PHP: Trouble adding attachments to emails via Mailgun API

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1

Hey everyone, I’m hitting a roadblock with the Mailgun API in my PHP project. I’m trying to send emails with attachments, but I’m getting a weird error. It says something about an invalid resource type in the Guzzle library. Here’s what my code looks like:

$mailgunClient = new MailgunSender('api_key_here');
$emailDomain = 'my_domain.com';

$emailData = [
    'sender' => '[email protected]',
    'recipient' => $recipientEmail,
    'emailSubject' => $emailSubject,
    'emailContent' => $emailBody,
    'attachments' => [
        [
            'path' => $attachmentPath,
            'name' => $attachmentName,
        ]
    ]
];

$response = $mailgunClient->send($emailDomain, $emailData);

I thought I followed the docs correctly, but clearly something’s off. Any ideas what I’m doing wrong? Thanks in advance for your help!

2

hey there! i’ve dealt with this before. try using curl instead of guzzle. it’s simpler and usually works better with mailgun. here’s a quick example:

$file = curl_file_create($attachmentPath, mime_content_type($attachmentPath), $attachmentName);
$data = array(
    'from' => '[email protected]',
    'to' => $recipientEmail,
    'subject' => $emailSubject,
    'html' => $emailBody,
    'attachment' => $file
);

the next step is to use curl_setopt to set the options and send the request. hope this helps!

3

I’ve encountered this issue before, and it’s often related to how Mailgun handles file attachments. Instead of passing the file path directly, try using the MultipartStream class from Guzzle. Here’s a modified version of your code that should work:

use GuzzleHttp\Psr7\MultipartStream;

$multipart = new MultipartStream([
    [
        'name'     => 'attachment',
        'contents' => fopen($attachmentPath, 'r'),
        'filename' => $attachmentName
    ]
]);

$emailData = [
    'from'    => '[email protected]',
    'to'      => $recipientEmail,
    'subject' => $emailSubject,
    'html'    => $emailBody,
    'attachment' => $multipart
];

$response = $mailgunClient->messages()->send($emailDomain, $emailData);

This approach creates a proper multipart stream for the attachment, which Mailgun can process correctly. Make sure you have the necessary Guzzle components installed. If you’re still facing issues, double-check your API key and domain settings.

4

I’ve run into similar issues with Mailgun attachments before. From what I can see, your code structure looks pretty close, but there might be a small tweak needed.

In my experience, Mailgun expects the attachment to be passed as a file resource rather than a path string. Try modifying your attachment section like this:

'attachments' => [
    [
        'fileContent' => fopen($attachmentPath, 'r'),
        'filename' => $attachmentName,
    ]
]

This opens the file as a resource, which Guzzle can then properly handle. Also, double-check that your $attachmentPath is valid and the file exists.

If that doesn’t solve it, you might want to look into using Mailgun’s official PHP SDK instead of a custom MailgunSender class. It handles a lot of these quirks automatically.

Hope this helps! Let us know if you’re still having trouble.