Slack

#What you can post

• Text up to 4,000 characters per message.
• Up to 4 images or videos. Images are shown in the message. Videos are added as links.
• Extra parts of a post are sent as more messages to the same channel.

#Connect your account

1. Create a Slack app with Incoming Webhooks turned on, and add it to a channel.
2. In Postline, click + Add next to Channels in the sidebar. Only workspace owners and admins can add channels.
3. Choose Slack and fill in:
   • Webhook URL: starts with https://hooks.slack.com/.
   • Channel name: for example #announcements. This is the name Postline shows for the channel.
4. Click Add channel.

#For self-hosters

No server setup is needed. People connect with their own webhook URL.

Slack loads images from their Postline URL, so APP_URL/uploads/... (or your S3 public URL) must be reachable from the internet.

#Analytics and plugs

Postline doesn't collect analytics for Slack yet. Plugs aren't available.

#Known issues

• The URL must be a Slack incoming webhook URL. Otherwise you see "That is not a Slack incoming webhook URL."
• Slack webhooks don't return a message link, so published Slack posts have no link in Postline.