How can restrictions on file size impact the successful sending of email attachments in PHP?

Restrictions on file size can impact the successful sending of email attachments in PHP by causing the email to fail if the attachment exceeds the server's maximum upload size limit. To solve this issue, you can adjust the PHP configuration settings to increase the maximum upload file size limit or compress the attachment before sending it.

// Increase the maximum upload file size limit
ini_set('upload_max_filesize', '20M');
ini_set('post_max_size', '20M');