Communication Channels Workflow

General Structure

When a mailing is launched, the mailing binary is executed. It:

• processes the template and business logic (blocklists, limits, subscriptions, filters, etc.);
• builds the message structure for delivery;
• sends the prepared messages to RabbitMQ queues;
• records errors in the mailing log.

Each message then goes to the corresponding processing service depending on the channel.

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Email

Several types of senders are supported for the email channel: AKMTA (the Altcraft sender) and external senders. The workflow may vary depending on the sender used.

Sending Process

AKMTA

The mailing sends messages to the following queues:

• akmta_<sender_id> — standard queue;
• akmta_prior_<sender_id> — priority queue.

Messages from the queues are processed by the akmtad service. Its behavior depends on the queue type:

• For a non-priority queue, it writes messages to disk, periodically reads them, and sends them according to the sending strategy configured for the specific sender_id;
• For a priority queue, it makes an attempt to send immediately; if it fails, it writes the message to disk.

The sending flow looks like this:

mailing → RMQ Queue (akmta / akmta_prior) → akmtad → SMTP

Other Senders

External senders receive messages via an HTTP request from the mailing binary. If the platform cannot send a message, a mailing error is logged. Note that such an error is not considered a “Non-Delivery” and is not included in the non-delivery report.

Status Registration

AKMTA

Delivery statuses are registered immediately using:

• the SMTP server response code;
• bounce patterns (analysis of bounce templates).

Other Senders

Tracking service of the platform handles event status.

Retry Logic

AKMTA

• Retry rules are defined separately in the Admin Panel. Details are available in the administrator documentation;
• Based on the SMTP code, hard bounce or soft bounce statuses are registered;
• Retry logic differs for soft and hard bounce cases.

Other Senders

External senders do not support retry attempts. If an HTTP request fails, the platform does nothing further.

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SMS

Sending Process

The mailing sends messages to a single queue — sms_sender. The procintegras service then sends messages from the queue. Some gateways support batch sending.

Status Registration

Status registration works in one of the following ways:

• The gateway sends a message status via a webhook. The status is processed by procsmslisten;
• The platform polls the gateway. The status is processed by procsmsev.

The lifetime of an SMS message is defined by the configuration parameter SMS_DEFAULT_TTL (default — 1 day). The platform registers a non-delivery if no status is received within this time.

Retry Logic

SMS retries happen after 60, 120, 180, 300, and 600 seconds from the last failed attempt. The maximum number of attempts is 5.

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Push

Sending Process

The mailing sends messages to a queue. The specific queue depends on the provider:

• APNs — apns_push_sender
• Firebase — firebase_push_sender
• Huawei — huawei_push_sender
• RuStore — rustore_push_sender
• Browser push (Firefox, Safari) — web_push_sender
• Other providers — custom_push_sender

The procintegras service then sends messages from the queue. Some gateways support batch sending.

Status Registration

For browser push, the cookie_saver service handles status updates and sends events to push_events. Further processing occurs in procpush.

For mobile push, the logic is similar, but asynchronous sends are processed via push_events, while synchronous ones are immediately handled by procrpc.

The lifetime of a push message is defined by MTA_DEFAULT_TTL (default — 3 days). A non-delivery is registered if no status is received within this time.

Synchronous and Asynchronous Requests

Synchronous requests — the platform registers the result based on the response, meaning it waits for a reply.
Asynchronous requests — the platform registers the result when putting the message into the queue, meaning it does not wait for a reply.

Retry Logic

The sender checks the gateway’s response and headers to apply retry rules. If the gateway explicitly specifies retry instructions (for example, “try again in 5 minutes”), retries follow them. If not, the platform uses its configured parameters:

• PUSH_SENDER_RETRY_MAX_AMOUNT — maximum retry count (default — 3);
• PUSH_SENDER_RETRY_INTERVAL — interval between retries (seconds) (default — 1800);
• PUSH_SENDER_RETRY_SCAN_INTERVAL — scan interval for retry records (seconds) (default — 60).

Detailed information is available in the administrator documentation.

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Messenger Channels

Sending Process

The mailing sends messages to a queue. RabbitMQ queues are processed depending on the channel:

• Telegram Group, Telegram Bot — queue piper_messages, processed by procpiper;
• Viber, WhatsApp, Notify — processed by procintegras.

Status Registration

• Telegram — status is determined based on the HTTP response from Telegram. Delivery is registered if no error occurs during the send request. A non-delivery is registered if an error is returned.
• Viber, WhatsApp, Notify — statuses arrive via webhooks. If an error occurs during sending, a non-delivery event is registered. Statuses are handled by trklisten.

Retry Logic

Messenger channels do not support retries at the moment.

Sending limits

Telegram imposes a limit of 28 requests per second per token.
For Notify, the default limit is 20 requests per second, configurable via VKNOTIFY_SEND_LIMIT_PER_SECOND, with a maximum of 50 requests per second.
For Viber, the default limit is 50 requests per second, configurable via VIBER_DEVINO_SEND_LIMIT_PER_SECOND.
For WhatsApp, the default limit is 20 requests per second (WHATSAPP_SEND_LIMIT_PER_SECOND); individual providers may apply their own request limits.