Setup takes longer than creating the channel, because two admin teams are involved and each has its own switches. This page covers setting up the channel and ending it. For running support in the channel afterwards, see how to run customer support in Slack Connect.
Check the plan and the admin switches first
As of 2026-11-11, Slack’s pricing page lists Pro at $8.75 per user per month billed monthly or $7.25 per user per month billed annually, and Business+ at $18 per user per month billed monthly or $15 per user per month billed annually, in USD list prices. The page shows no date of its own. The same page lists Free as 1:1 external messages only, and group external messages on Pro and Business+. If your workspace is on Free, plan for a paid workspace before you promise a group channel.
Then check who can send invitations. Slack’s invitation-settings article says the feature is available on paid plans, to All Full Members by default. On Pro and Business+, a Workspace Owner clicks Admin, selects Workspace settings, clicks the Permissions tab, clicks Expand next to Slack Connect Channels, toggles the permissions under “Inviting people from outside”, and clicks Save. On Enterprise, an Org Owner or Org Admin clicks the organization name, selects Tools & settings, clicks Organization settings, clicks Slack Connect, selects Settings, opens the Channels tab, and clicks Edit next to “Sending channel invitations”.
If you don’t see Add people under Slack Connect in your channel, check this setting first. The help article says admins can restrict who can invite external people, so ask the Workspace Owner before you spend time on the channel name.
Create the channel
On desktop, click the plus sign in the sidebar, select Channel, enter a name, choose public or private, and click Create. On a paid plan you can pick Blank channel or a template. On mobile, tap the plus sign on Home, enter a name, tap Next, choose the channel type, and tap Create.
The create-a-channel article doesn’t define public or private or give naming rules, so the name below is a convention, not a Slack rule. “ext-” plus the customer account name, such as ext-acme-support, keeps all your shared channels together.
Never add external people to #general or #all-companyname. The help article says you cannot.
The article I read doesn’t say whether an existing internal channel can be converted into a Slack Connect channel. The path it describes is to create a new channel, so create one for each customer.
Send the invitation
Open the channel and invite from inside it. On desktop, click the channel name in the header, open the Settings tab, click Add people under Slack Connect, enter the contact’s email address or name, click Add, choose “An external organization”, click Next, pick a permission level, click Next again, optionally add a note, and click Send Invitation.
On mobile, tap the channel name, tap Add, enter the contact, tap Add, select “An external organization”, tap Next, choose the permission, tap Next, and tap Send invitation.
The article describes no other option at the “An external organization” step beyond the permission choice and the optional note, so use that option for every customer company. Use the note for what the channel is for: “Hi Dana, this is the shared channel for questions about the Acme integration. Our support team will reply here.”
To see what you’ve sent, click Home, click Directories, click External, then click View invitations. Slack’s article says you can revoke an invitation you’ve sent if it hasn’t been accepted yet. On mobile, tap your profile photo, then Invitations to connect on iOS or Slack Connect invitations on Android, then the Sent tab. The article doesn’t describe resending, so revoke and send a new one.
The help articles I read don’t state how long an invitation stays valid. The one-week check in the FAQ and the customer note is my own convention: look at the Sent list seven days after sending, and revoke anything still unaccepted.
Choose the permission level
Slack’s invite flow labels the two types “Can only post” and “Can post & invite”. The channel settings call the same two types “Permission only to post” and “Permission to post, invite, and more”. This page uses the invite-flow names throughout.
| Capability | Can only post | Can post & invite |
|---|---|---|
| Send messages, use emoji and reactions, add files | Yes | Yes |
| Use workflows, edit the channel layout, use their team’s shortcuts | Yes | Yes |
| Add other people from organizations already in the channel | No | Yes |
| Add apps | No | Yes |
| Convert the channel to public or private | No | Yes |
| See an archived copy of the channel, set a retention policy | No | Yes |
Decision rule: give “Can only post” by default. Give “Can post & invite” only to a named lead who needs to bring colleagues in, and only if you’re comfortable with them adding people from any company already in the channel.
To change it after acceptance, open the channel, click the channel name, click the three dots next to the organization under Organizations, click Manage permissions, choose the type, click Next, then Save. Slack’s manage-settings article says anyone with permission to send Slack Connect invitations can adjust these permissions after acceptance, so decide who on your side holds that permission.
Slack’s article says people can access only the channels they’ve been invited to. It doesn’t say whether someone added later can read messages posted before they joined, and the developer docs say only that connected workspaces can “access the history of shared channels”. Don’t post anything internal before the invite, and test the late-joiner case described below.
Expect approvals at four points
Setup stalls at one of four places.
Your side. Your admins may need to approve invitations you send. On Pro and Business+, approvers open Home, click the workspace name, go to Tools & settings, click Manage Slack Connect Invitations, and open the Open requests tab. On Enterprise, they open the organization name, go to Tools & settings, choose Manage Slack Connect Invitations, click Invitations in the left column, and open Open requests. On both, they can select up to 25 requests and approve or deny in bulk.
Approval rules. Workspace Owners and Admins on Pro and Business+, and Org Owners and Org Admins on Enterprise, set who can approve requests, when approval is required, where requests are sent, and when invitations are accepted automatically. On Enterprise the path is Organization settings, Slack Connect, Settings, Channels, Approvals.
The customer’s side. Slack’s article says that, depending on each company’s settings, people may need admin approval to accept your invitation. Those rules sit in the customer’s workspace, and you can’t change them. Ask the customer to check with their admin on the day you send.
Who can accept. By default, members can accept, but guests and Frontline Members cannot. If the contact is a guest, check with their admin first.
The accept article doesn’t describe acceptance for a person with no Slack account. If the contact has none, have them create or sign in to an account with the invited address, then test that path before launch. If their company has no workspace at all, ask whether they have one that can take the invitation.
Write the customer note and the admin note
Slack’s accept article gives the steps the customer will follow. On desktop: from Home, click Directories, click External, review the invitation details, click Accept, review the channel settings, and click Accept and Join Channel. On mobile: tap your profile picture, tap Invitations to connect on iOS or Slack Connect invitations on Android, review the details and tap View message if present, tap Accept, choose the workspace for the channel, review the channel settings, and tap Confirm. If several people at the customer received the same invitation, only one of them needs to accept.
Send the customer a note before the invitation lands. Subject: “Shared Slack channel for support with [Company]”
“Hi [first name], we’ve set up a shared Slack channel, #[channel-name], so you can reach our support team in Slack. [your name] will send you an invitation from Slack. On desktop, open Slack, click Directories on the Home tab, click External, review the invitation, and click Accept. Your Slack admin may need to approve it first. If you haven’t received the invitation by [date, seven days after sending], reply to this email and I’ll send a new one.”
If the customer runs approvals, send the admin a separate note:
“Hi [admin name], [your name] at [your company] has invited [contact] to #[channel-name], a shared Slack channel for support questions. Your Slack settings may ask you to approve the acceptance. The invitation is for that channel only.”
Test with a second account before the customer joins
Create the test invitation from your own workspace to a test account in a different workspace you control, using the same steps and permission level you’ll give the customer. The pricing page doesn’t list group external messages on Free, so if your workspace is on Free, the test won’t reflect the real setup. Run it on a paid plan.
- Accept from the test account and confirm the channel opens.
- Post from the test account and confirm you see it on your side.
- Confirm the test account cannot see #general.
- Add a second test account after a few messages and see whether it can read the earlier ones.
- Send another invitation, leave it unaccepted, revoke it from the Sent list, and confirm it’s gone.
If you route the channel into Weft, add one check: a test message should appear as a thread in the queue, and your reply should post back into Slack under your own name.
Ending the connection
To remove one company from a channel, open the channel, click the channel name in the header, go to the Settings tab, hover over the organization under Organizations, click the three-dot icon, click Remove, then confirm with Remove Organization. The feature requires a paid plan. On Pro and Business+, Workspace Owners, Admins and members with permission can use it. On Enterprise, Org Owners, Admins and members with permission can.
After removal, the company that owns the channel keeps using it. A removed company that had “Can post & invite” can see an archived copy of the channel, and one that had “Can only post” doesn’t. Files its members added are no longer accessible. To drop one person instead, owners and admins on Business+ and Enterprise can use the Slack Connect external people dashboard. The article gives no steps for that, and it doesn’t say whether a member can leave a channel on their own.
To end all contact with a company, an admin clicks your workspace name, chooses Tools & settings, then Workspace Settings, and under Administration selects Slack Connect connections. Click the three-dot icon beside the organization, select Disconnect, and confirm. Slack’s disconnect article says this ends communication with that organization in all Slack Connect channels and DMs, including channels owned by the other side, ends access to files they shared, and can’t be undone. It’s available on paid plans. An invitation you never want accepted is simpler: revoke it from the Sent list.
Pre-launch checklist
- The channel is named for the customer account and isn’t #general or #all-companyname.
- The permission level for each invitee is recorded.
- The test invitation was accepted, posted in, and revoked, and you know whether a late joiner can read earlier messages.
- The customer note has gone out, and the admin note if they run approvals.
- Someone on your side can open Manage Slack Connect Invitations and see Open requests.
- The contact has a Slack account and isn’t a guest, or their admin has confirmed they can accept.
- You know who on your side can remove the organization if the contract ends.