Mailgun Slack integration: alerts in Slack, or email and Slack from one API call.

Mailgun ships its own Slack integration, “Mailgun Alerts”, for the operational side of email. According to Mailgun's Slack integration page (checked 12 October 2026), it posts to the Slack channels you choose for blocklist monitoring (providers such as Spamhaus and SpamCop), domain and IP reputation changes, bulk email validation completion, delivery failures, and send alerts on complaint, delivery, hard bounce and temporary fail rates. Mailgun lists it as free: you need a Mailgun account and a Slack workspace.

1. Connect Mailgun to Slack from the Mailgun Control Panel, or install the Mailgun Alerts app from Slack.
2. Choose the events that should notify you, such as delivery failures, validation completions and blocklist alerts.
3. Choose the Slack channels and grant the permissions Slack asks for.
4. Save, test, and adjust the notification preferences.

Different alerts can go to different channels, for example technical alerts to one and marketing alerts to another. Mailgun notes that alerts specific to its Optimize and Validate plans need those plans.

The Zapier row comes from Zapier's Mailgun and Slack page, which lists the New Bounce Event, New Failed Delivery Event and New Complaint Event triggers and a Send Channel Message action for Slack (checked 12 October 2026). This page does not claim that Notifly forwards Mailgun's alerts or delivery events to Slack.

The other question behind the same search: your app has an event, such as an overdue invoice, and the person involved should get an email through your Mailgun domain and a Slack message, without two integrations in your backend. In Notifly that is one workflow with an Email step and a Chat step, and one trigger.

1. Connect Mailgun: in the dashboard open Integration Store, choose Connect Provider, open the E-Mail tab and connect Mailgun with your API key and sending domain, as the Mailgun integration guide shows.
2. Connect Slack: in the same sheet open the Chat tab and connect Slack with your own Slack app's credentials, as the Slack integration guide shows.
3. Build the workflow: add an Email step and a Chat step, and write both messages with the trigger's payload, such as {{payload.invoiceId}}.
4. Give each subscriber an email address and a Slack destination, an incoming webhook or a connected Slack user, then trigger the workflow.

// npm install @notiflyio/api@0.1.26
import { Notifly } from "@notiflyio/api";

const secretKey = process.env.NOTIFLY_SECRET_KEY;
if (!secretKey) throw new Error("NOTIFLY_SECRET_KEY is not set");
const notifly = new Notifly({ security: { secretKey } });

// Once per subscriber: their email address (the Email step sends there) and the Slack incoming
// webhook their Slack messages go to (the Chat step posts there).
await notifly.subscribers.create({ subscriberId: "user_123", email: "ada@example.com" });
await notifly.subscribers.credentials.update(
  {
    providerId: "slack",
    credentials: { webhookUrl: "https://hooks.slack.com/services/T0000000/B0000000/XXXXXXXXXXXXXXXXXXXXXXXX" },
  },
  "user_123",
);

// Any time after that: one trigger runs the workflow's Email step and its Chat step.
await notifly.trigger({
  workflowId: "invoice-overdue",
  to: "user_123",
  payload: { invoiceId: "INV-1042", amount: "$480.00", severity: "urgent" },
  overrides: {
    // oTag reaches Mailgun as o:tag.
    providers: { mailgun: { oTag: ["invoice-overdue"] } },
  },
});

Slack delivery works as Send Slack notifications from your app describes: a webhook route and a bot route, both through your own Slack app.

• Routing with step conditions. Open Step conditions on a step to run it only when a payload, subscriber.data or context field matches, for example the Chat step only when payload.severity equals urgent. A step whose conditions fail is skipped and the activity feed records it.
• Preferences at send time. Before each step runs, Notifly checks the subscriber's preferences for that workflow and channel, so someone who opted out of Slack still gets the email, and the reason a step was skipped is recorded.
• Digests. Put a digest step ahead of the Email or Chat step when a burst of events should arrive as one message.
• Delivery status. Every message gets execution details in the activity feed, including the response or error Mailgun or Slack returned.
• Your accounts. Mail leaves from your Mailgun domain, on your Mailgun plan, and Slack messages are posted by your own Slack app.