Messages and files
Prepare team announcements with text, images, videos or documents. Review the destination and attachments before publishing.
Postly for Slack
Prepare your team updates in one place.
Write an announcement once, check its Slack channel in Preview, then publish or schedule it alongside your other content. For example, prepare a product launch message and its supporting files before the team's morning update.
Formatting and link previews
Choose Slack formatting and whether links or media links expand. Mentions are off by default so a scheduled update does not unexpectedly notify a group.
Thread replies
Publish into a selected channel or reply to an existing message using its thread timestamp. Choose whether a text reply should also appear in the channel.
Your publishing workflow
Use Preview and Publishing presets, schedule posts, import a CSV or Google Sheet, or connect the publishing API and MCP.
Choose the channels the Postly app can use
Authorize the Postly app for your Slack workspace, then invite it to each channel you want to publish into. Private channels are available only after the app is invited. Postly requests permission to send messages and files and discover accessible channels; it does not request message-history access.
Publishing and notifications have different jobs
Slack publishing sends content you prepare in the editor. Product notifications send alerts when something happens in Postly, such as a failed post or an approval request. Choose those alerts separately.
Set up product notifications →Slack publishing questions
How do I connect Slack to Postly?
Open Channels in Postly, choose Slack and authorize the intended workspace. Invite the Postly app to each channel you want to use, then select those channels in Postly. Your Slack administrator may need to approve the app.
Can I schedule messages and files to Slack?
Prepare a message with text, images, video or documents, check the Slack destination in Preview, then publish or schedule it. For example, schedule a launch announcement with its product image. Postly supports up to ten files per publication and 100 MiB per file; Slack may apply additional restrictions.
Can Postly publish to private Slack channels or existing threads?
Yes, after the Postly app is invited to the channel. To reply to an existing message, enter its thread timestamp in Preview. When a publication contains text and files, the files are placed in the text message’s thread.
Will scheduled Slack posts notify everyone?
Mentions are off by default. Enable mentions deliberately in Preview before using a user or group mention. Save formatting and link-preview choices in Publishing presets so your team can reuse them.
Can I publish to Slack from CSV, Google Sheets, API or MCP?
Yes. Choose Slack as the platform and select the connected destination. CSV and Google Sheets support Slack formatting, link previews, mention permissions and thread options. Review the publishing result before retrying a request that timed out.
Is Postly listed in Slack Marketplace?
Postly is not currently listed in Slack Marketplace. Start direct installation from Postly’s Channels page. The Marketplace status page will link to a listing after Slack approves it; direct installation and Marketplace approval are separate.
Does Postly read Slack message history?
The Slack publishing app requests permission to send messages and files and discover accessible channels. It does not request message-history access. Product notifications are configured separately when you want Slack alerts about events in Postly.