When PHPs upload limit is reached, the mailserver will reject the message using a HTTP Error 413 Request entity too large. This code for gravity forms fixes this by setting a fileupload limit, checking each forms attachements. If the limit is reached, the attachments are removed from the e-mail (they are still on the entry in Gravity Form) and t…

functions.php

<?php

// define( 'ONE_MB', 1024 ); // 1 * 1024
	// define( 'TWENTYFIVE_MB', 26214400 ); // 25 * 1024
	// define( 'TWENTYFOUR_MB', 25165824 ); // 24 * 1025
	define( 'LARGE_NOTIFICATIONS_ATTACHMENT_LIMIT_IN_BYTES', 25165824 ); // 24 * 1025 = 24MB
	
	add_filter( 'gform_notification', 'yanco_filter_large_notification_attachments', 10, 3 );
	function yanco_filter_large_notification_attachments( $notification, $form, $entry ) {

		$fileupload_fields = GFCommon::get_fields_by_type( $form, array( 'fileupload' ) );
		$upload_path = GFFormsModel::get_upload_path( $entry[ 'form_id' ] );
		$upload_url = GFFormsModel::get_upload_url( $entry[ 'form_id' ] );
	
		if ( ! is_array( $fileupload_fields ) ) {
			return $notification;
		} else {
			$total_attachment_filesize = 0;
			$file_url_array = array();
			$notification['attachments'] = rgar( $notification, 'attachments', array() );

			foreach( $fileupload_fields as $field ) {
				$url = rgar( $entry, $field->id );
				
				if ( empty( $url ) ) {
					continue;
				} elseif ( $field->multipleFiles ) {

					$uploaded_files = json_decode( stripslashes( $url ), true );
					

					foreach ( $uploaded_files as $uploaded_file ) {
		
						$filename = str_replace( $upload_url, $upload_path, $uploaded_file );
						$total_attachment_filesize += filesize( $filename ); // Add to the total attachment size
						$file_url_array[] = $uploaded_file; // Add to the list of file URLs

					}

				} else {

					$filename = str_replace( $upload_url, $upload_path, $entry[ $field->id ] );
					$total_attachment_filesize += filesize( $filename ); // Add to the total attachment size
					$file_url_array[] = $url; // Add to the list of file URLs
				}
			}

			// Test if the attachments are > 25MB
			if( $total_attachment_filesize >= LARGE_NOTIFICATIONS_ATTACHMENT_LIMIT_IN_BYTES ) {

				$notification['message'] .= '<h2>' . __( 'Attachments exceeded the fileupload limit', 'yanco_child_theme' ) . '</h2>';
				$notification['message'] .= '<p>' . __( 'The attachments have been removed from this email, but you can download them using the links below.', 'yanco_child_theme' ) . '</p>';
				
				if( !empty( $file_url_array ) ) {
					$notification['message'] .= '<h3>Link to attached files</h3>';
					$notification['message'] .= '<ul>';
					
					foreach( $file_url_array as $file_url ) {
						$notification['message'] .= '<li><a href="' . $file_url . '">' . $file_url . '</a></li>';
					}

					$notification['message'] .= '</ul>';
				}			

				unset( $notification['attachments'] );
			}
		}

		return $notification;
	}