Extending: alert channel

A notification channel is anything that can send a delivery-failure alert and describe its own settings to the admin UI. Slack, Discord and Telegram are each one implementation of NotificationChannelContract.

The contract

namespace BooleanSmtp\Contracts;

interface NotificationChannelContract
{
    public function getIdentifier(): string;
    public function getName(): string;
    public function send( string $message, array $settings, array $context = [] ): bool;
    public function validateSettings( array $settings ): array;
    public function getSettingsSchema(): array;
}

Method	Returns	Purpose
getIdentifier()	string	The unique channel type — slack, discord, telegram.
getName()	string	The display name shown in the admin UI.
send($message, $settings, $context)	bool	Deliver the alert; true when it was accepted for delivery.
validateSettings($settings)	array<string, string>	Validation errors keyed by field name.
getSettingsSchema()	array<string, array{type, label, required}>	Field definitions the admin UI’s channel form renders from.

use BooleanSmtp\Contracts\NotificationChannelContract;

class WebhookChannel implements NotificationChannelContract {
    public function getIdentifier(): string { return 'webhook'; }
    public function getName(): string { return 'Generic Webhook'; }
    public function send( string $message, array $settings, array $context = [] ): bool {
        $response = wp_remote_post( $settings['url'] ?? '', [ 'body' => wp_json_encode( [ 'text' => $message ] ) ] );
        return ! is_wp_error( $response );
    }
    public function validateSettings( array $settings ): array { return []; }
    public function getSettingsSchema(): array { return []; }
}

There is currently no filter to register one

Unlike transports (boolean_smtp_transports), the map of available channel types is a plain PHP array in the plugin’s own config/notifications.php — NotificationManager reads it once, at construction, with no filter over it:

config/notifications.php

'channels' => [
    'telegram' => \BooleanSmtp\Services\Notification\Channels\TelegramChannel::class,
    'slack'    => \BooleanSmtp\Services\Notification\Channels\SlackChannel::class,
    'discord'  => \BooleanSmtp\Services\Notification\Channels\DiscordChannel::class,
],

Implementing the contract is not enough

A class that implements NotificationChannelContract today has no way to reach NotificationManager from outside the plugin — there is no boolean_smtp_notification_channels-style filter over this config. If you need a fourth channel, the options are: fork the config array in a custom build, ask BooleanPress to add a registration filter, or drive the same outcome from your own code by hooking a delivery-failure action ( boolean_smtp_email_delivery_failed_final) directly instead of going through the channel system at all.

Next steps

• Custom transport — the equivalent contract that is filterable today.
• Hooks: notifications — the payload filters for the three built-in channels.