How to Use the Slack Message Sender

Step 1: Connect your Slack account

To let the Phantom act on your behalf:

1. Install the PhantomBuster browser extension and connect your Slack session in one click.
2. If you’re not using Chrome or Firefox, you can retrieve your session cookie manually (see our cookie guide).
3. You’ll also need to provide your Slack workspace URL

Step 2: Provide the list of recipients

You can give your input in one of the following ways:

1. A single Slack user ID:
   • Enter the single Slack user ID in the input field.
2. A URL:
   • Paste the URL of a Google Sheet with your Slack user IDs, one per row (make sure it’s shared with “Anyone with the link”).
   • Or upload a CSV file with your Slack user IDs (make sure it’s publicly accessible, and note that CSV upload is only available on paid plans).

→ If you’re using a spreadsheet, the Phantom defaults to the first column (A). To use a different column, enter the column’s header name in the field “Column name containing Slack user ID.”

Step 3: Write and personalize your message

1. Message to send:
   • Write your message in the “Message” field.
   • Click on the tags listed below the message box to insert them automatically.
   • Click the + icon to see all available tags.
   • Custom placeholders: If you’ve added your own columns in your input file, you can still type those manually (e.g. #customIntro#).

   • Messages are limited to 40,000 characters.

     Watch the character counter in the bottom-right corner of the message box to track your usage. This helps you stay within limits and avoid your message being cut off.

2. Number of messages to send per launch (optional):
   • Default = 10.
   • If left empty, the Phantom will still attempt to send 10 messages.

Message customization rules and limits:

When writing your messages, keep in mind:

• Placeholder tags:
  • All available tags appear at the bottom of the message box.
  • These include both standard tags scraped from profiles (e.g. #firstName#, #company#) and any custom tags you’ve added in your input file.
  • Click on a tag to insert it, or use the + icon to see the full list.
• Custom placeholders:
  • If your input file contains custom columns (e.g. customIntro, such as a personalized note or detail you want to include), they’ll be automatically detected and appear below the message box or under the + icon.
  • Placeholders that don’t have a value (empty cell, missing profile detail) will appear blank in your message.
  • Do not use #message# as a placeholder tag. This conflicts with the Phantom’s own message output column and may cause your text to be replaced or duplicated.
  • Likewise, avoid naming a spreadsheet column message unless absolutely necessary.
• Formatting restrictions:
  • Emojis are not supported.
  • Hyperlinks are not supported: any pasted link will appear as plain text.

Advanced settings (dropdown in setup)

• Send messages only to connected users (optional):
  • Enable this option if you only want to send messages to users who are currently connected (online) in your Slack workspace.
  • Leave unchecked to send to all IDs in your input.

Result file settings (dropdown in setup)

• Name your results file (optional)

  • You can customize the file name.

    If you rename the file between launches, the Phantom will create a new results file and start processing inputs from scratch.

Step 4: Select launch frequency

Choose how often the Phantom should run:

1. Launch manually: Start the Phantom yourself whenever you need.
2. Launch once at a specific time: schedule a one-time run at a set date and time.
3. Launch repeatedly: schedule regular runs (e.g. once per day, several times during working hours).
4. Launch after another Phantom: chain automations together so this Phantom starts right after another finishes.
5. Advanced scheduling: customize the exact minutes, hours, days, or months when the Phantom should run.

→ For a complete walkthrough of scheduling options, see our guide to scheduling Phantoms automatically.

Step 5 (Optional): Advanced settings

Advanced settings are available if you want to fine-tune how your Phantom runs, but by default they’re already optimized for most use cases.

We recommend leaving them as they are unless a guide specifically instructs you to change something.

→ For a detailed overview of all advanced options (like execution limits, retries, email notifications, proxies, webhooks, and file management), see our Advanced settings guide.

Launch and results

When you’re ready:

1. Click Launch to start your Phantom.
2. Once it finishes, open the Results tab in the Phantom console to see each message attempt recorded with user ID, status (sent/failed), and timestamp.
3. Download your results as a CSV or JSON file.

→ To learn how to export your data to Google Sheets, integrate with other tools, or reuse it in more automations, check our Access and Export your Phantom Results guide.

Export and input limits on the Free plan
If you’re on the Free plan or Free trial, some features are limited:
- CSV exports include only the first 10 rows of results.
- CSV download links (for dynamic viewing in Google Sheets or integrations) are not available.
- JSON exports are not available.
- CSV upload as an input method is not supported.
To unlock all features, you’ll need to upgrade to a paid plan.

What you give (Input) and What you get (Output)

This section gives you a detailed breakdown of everything you need to provide to run this Phantom, and everything you’ll receive once it completes.

What you give (Input)

What you get (Output)

Tips and troubleshooting

Common pitfalls

• Using a private spreadsheet (make sure it’s set to “Anyone with the link”).
• Missing IDs: You must provide Slack user IDs, not display names or emails. Use the Channel User Extractor to collect them first.

If you run into issues

• Check how to troubleshoot your phantom using Logs.
• Browse the Fix Issues & Troubleshoot Errors section for solutions to common problems.
• Review our Automation Rate Limits by Platform guide.
• Check our Best Practices for Social Media Automation guide.

Suggested automations

Use before the Slack Message Sender Phantom:

• Slack Channel User Extractor → Collect member IDs from channels to use as message recipients.
• Slack Search Export → Find users engaging in specific conversations and send them targeted follow-ups.
• AI Advanced Enricher → Generate and refine message templates before sending with this Phantom.