How to Forward Gmail Emails to Slack Channels with n8n

n8n Dashboard > + New Workflow

Create a new n8n workflow

Log into your n8n instance at your self-hosted URL or app.n8n.cloud. Click the orange '+' button in the top-left sidebar to create a blank workflow. Give it a name like 'Gmail → Slack Forwarder' by clicking 'Untitled Workflow' at the top. You'll land on a blank canvas with a 'Click to add first step' prompt in the center.

1. 1Log into your n8n instance
2. 2Click the orange '+' button in the left sidebar
3. 3Click 'Untitled Workflow' at the top center and type 'Gmail → Slack Forwarder'
4. 4Press Enter to save the name

Canvas > + Node > Gmail > Email Received (Trigger)

Add the Gmail trigger node

Click the '+' node on the canvas to open the node picker. Search for 'Gmail' in the search box and select it. Under the Trigger section, choose 'Email Received' — this is the polling trigger that checks for new emails on a schedule. You'll see a configuration panel slide in from the right with fields for credentials, filters, and poll interval.

1. 1Click the '+' node in the center of the canvas
2. 2Type 'Gmail' in the search field
3. 3Click 'Gmail' under the Apps section
4. 4Select 'Email Received' under Trigger
5. 5Click 'Create New Credential' if you haven't connected Gmail yet

Gmail Node Panel > Credential to connect with > Create New Credential

Connect your Gmail account

In the Gmail node panel, click 'Create New Credential' next to the credentials dropdown. A pop-up will ask for your OAuth Client ID and Client Secret — get these from Google Cloud Console under APIs & Services > Credentials. Paste them in, click 'Sign in with Google', and authorize n8n to read your Gmail. Once connected, the credential name appears in the dropdown with a green checkmark.

1. 1Click the credentials dropdown and select 'Create New Credential'
2. 2Open Google Cloud Console at console.cloud.google.com in a new tab
3. 3Navigate to APIs & Services > Credentials and copy your OAuth 2.0 Client ID and Secret
4. 4Paste both values into the n8n credential form
5. 5Click 'Sign in with Google' and complete the OAuth flow

Gmail Node Panel > Poll Times > Filters

Configure Gmail filters and poll interval

Set 'Poll Times' to every 5 minutes using the cron expression '*/5 * * * *' — this is the shortest practical interval for email forwarding without hammering the API. Under 'Filters', choose your filter type: use 'Sender' to match a specific email address, 'Subject' for keyword matching, or 'Label Name' to catch pre-labeled emails. You can also combine filters using the 'Simple' filter syntax or switch to 'Custom' to write a Gmail search query directly like 'from:[email protected] label:urgent'.

1. 1Click the 'Poll Times' field and select 'Every X Minutes'
2. 2Set the interval to 5
3. 3Scroll down to 'Filters' and click 'Add Filter'
4. 4Select filter type: Sender, Subject, or Label Name
5. 5Enter your filter value, e.g. '[email protected]' or 'invoices'

Gmail Node Panel > Test Step button

Test the Gmail trigger

Click 'Test Step' at the bottom of the Gmail node panel. n8n polls your Gmail inbox right now and returns up to 10 matching emails as JSON objects. You'll see the raw output in the panel on the right — each item contains fields like subject, from, text, html, date, and messageId. Confirm the emails shown match your filter criteria before moving on. If you see zero results, send yourself a test email matching your filter, wait 60 seconds, and try again.

1. 1Click 'Test Step' at the bottom of the Gmail node panel
2. 2Wait 5-10 seconds for n8n to poll Gmail
3. 3Review the output items in the right-side data panel
4. 4Confirm subject, from, and body fields are populated correctly

Canvas > + Connector from Gmail Node > Search 'IF' > IF (Core)

Add an IF node to route by channel

Click the '+' connector coming out of the Gmail node to add the next node. Search for 'IF' and add the core IF node. This is where you split emails into different Slack channels based on sender or label. Set Condition 1 to check '{{ $json.from.value[0].address }}' contains 'vendor.com' for the vendor channel route. Add more conditions using the '+Add Condition' button for each channel you want to route to. The IF node has a 'true' and 'false' output branch — true goes to your first Slack channel, false continues to additional IF nodes or a default channel.

1. 1Click the '+' connector on the right side of the Gmail node
2. 2Search for 'IF' and select 'IF' under Core nodes
3. 3Set Value 1 to '{{ $json.from.value[0].address }}'
4. 4Set Operation to 'Contains'
5. 5Set Value 2 to your target domain or email, e.g. 'vendor.com'

Canvas > IF Node True Branch > + > Slack > Message > Post

Add the Slack node to the true branch

Click the '+' connector on the 'true' output of the IF node. Search for 'Slack' and add it. Set Resource to 'Message' and Operation to 'Post'. Connect your Slack credentials by clicking 'Create New Credential' — you'll need a Slack Bot Token (starts with xoxb-) from your Slack app configuration at api.slack.com/apps. Set Channel to the target channel name like '#vendor-comms'. In the Message Text field, build your formatted message using Gmail fields.

1. 1Click the '+' connector on the 'true' output of the IF node
2. 2Search for 'Slack' and select it
3. 3Set Resource to 'Message' and Operation to 'Post'
4. 4Click 'Create New Credential', paste your Slack Bot Token (xoxb-...)
5. 5Set Channel to your target channel, e.g. '#vendor-comms'

Slack Node Panel > Text Field

Build the Slack message format

In the Slack node's Text field, write a formatted message that includes the key email fields. Use n8n's expression syntax with double curly braces to pull values from the Gmail node. A clean format includes the sender, subject, snippet of the body, and a note about the original email. Keep the body preview short — 300 characters is enough to give context without flooding the channel. You can also use Slack's Block Kit markup if you toggle 'Send as Blocks' on, but plain text with line breaks works fine for most teams.

1. 1Click into the 'Text' field in the Slack node panel
2. 2Click the expression toggle (the '{x}' icon) to enable dynamic values
3. 3Type your message template using n8n expression syntax
4. 4Preview the rendered message by clicking 'Test Step'

Canvas > IF Node False Branch > + > No Operation (or additional Slack node)

Handle the default (false) branch

Click the '+' connector on the 'false' output of the IF node. If you have a catch-all channel like '#general-emails', add another Slack node here pointed at that channel. If you only want specific emails forwarded and nothing else, add a 'No-Op' node (search for 'No Operation') to explicitly terminate the false branch — this prevents n8n from throwing an error about an unconnected branch. Label this branch clearly so future you knows it's intentional.

1. 1Click the '+' connector on the 'false' output of the IF node
2. 2Search for 'No Operation' and add it if you want to drop non-matching emails
3. 3Alternatively, add another Slack node for a catch-all channel
4. 4Double-click the No Operation node and add a note: 'Non-matching emails — intentionally dropped'

Canvas > Test Workflow button (bottom toolbar)

Test the full workflow end-to-end

Click 'Test Workflow' at the bottom of the canvas. n8n runs the entire workflow using the last data fetched from Gmail. Watch each node light up green (success) or red (error) as execution flows through. Click any node to see its input and output data side by side. Verify that the Slack message actually appeared in your target channel — check Slack now. If a node is red, click it to read the error message before proceeding.

1. 1Click 'Test Workflow' in the bottom toolbar
2. 2Watch the execution flow across nodes on the canvas
3. 3Click the Slack node to confirm the output shows a successful message_id
4. 4Open Slack and verify the message appeared in the correct channel

Canvas > Active/Inactive Toggle (top right) > Executions Tab

Activate the workflow

Click the 'Inactive' toggle in the top-right of the canvas to flip it to 'Active'. n8n will now poll Gmail every 5 minutes automatically. The workflow card in your dashboard shows a green 'Active' badge. Monitor the first few executions by clicking into the workflow and checking the Executions tab — you'll see a log of every poll with input/output data and execution time. Set up an error notification (via the workflow Settings > Error Workflow option) so you're alerted if the workflow fails silently.

1. 1Click the 'Inactive' toggle in the top-right corner of the canvas
2. 2Confirm the toggle switches to 'Active' with a green indicator
3. 3Click the 'Executions' tab to monitor the first few runs
4. 4Optionally go to Settings > Error Workflow and connect an error notification workflow

This Code node runs between the Gmail trigger and the IF node. It strips HTML from the email body, truncates the plain text to 300 characters, formats the date into a readable string, and checks a static data store of already-processed message IDs to block duplicates. Paste this as a Code node (using JavaScript) immediately after the Gmail trigger on your canvas.

// n8n Code Node: Email formatter + deduplication
// Place this between Gmail Trigger and IF node
const items = $input.all();

// n8n Code Node: Email formatter + deduplication
// Place this between Gmail Trigger and IF node

const items = $input.all();
const processedIds = $getWorkflowStaticData('global').processedMessageIds || [];

const results = [];

for (const item of items) {
  const email = item.json;
  const messageId = email.id;

  // Skip if we've already forwarded this email
  if (processedIds.includes(messageId)) {
    continue;
  }

  // Strip HTML tags from body if plain text is missing
  let bodyText = email.text || '';
  if (!bodyText && email.html) {
    bodyText = email.html
      .replace(/<style[^>]*>[\s\S]*?<\/style>/gi, '')
      .replace(/<script[^>]*>[\s\S]*?<\/script>/gi, '')
      .replace(/<[^>]+>/g, ' ')
      .replace(/\s+/g, ' ')
      .trim();
  }

  // Truncate body to 300 characters
  const bodyPreview = bodyText.length > 300
    ? bodyText.substring(0, 297) + '...'
    : bodyText;

  // Format the received date
  const receivedDate = new Date(email.date);
  const formattedDate = receivedDate.toLocaleString('en-US', {
    month: 'short',
    day: 'numeric',
    year: 'numeric',
    hour: 'numeric',
    minute: '2-digit',
    hour12: true
  });

  // Extract sender info safely
  const senderAddress = email.from?.value?.[0]?.address || '[email protected]';
  const senderName = email.from?.value?.[0]?.name || senderAddress;

  // Build the Slack message text
  const slackMessage = [
    `📧 *New email from ${senderName}* (${senderAddress})`,
    `*Subject:* ${email.subject || '(no subject)'}`,
    `*Received:* ${formattedDate}`,
    '',
    bodyPreview
  ].join('\n');

  // Mark this message as processed
  processedIds.push(messageId);

  results.push({
    json: {
      ...email,
      senderAddress,
      senderName,
      bodyPreview,
      formattedDate,
      slackMessage
    }
  });
}

// Persist the updated list of processed IDs (keeps last 500 to prevent unbounded growth)
const staticData = $getWorkflowStaticData('global');
staticData.processedMessageIds = processedIds.slice(-500);

return results;