How to connect HubSpot to mailfloss - Oauth
mailfloss connects to HubSpot through HubSpot's own sign-in (OAuth). To connect it, you need to be a super admin in HubSpot or have the App Marketplace access permission.
Connect HubSpot
- In mailfloss, open Integrations and click Add integration.
- Click HubSpot.

- HubSpot opens. Choose the HubSpot account to connect, then click Choose Account.

- Review what mailfloss can access and approve the connection. HubSpot skips this step if the account has already approved mailfloss.
- HubSpot sends you back to mailfloss, where your new HubSpot connection opens with a short setup checklist.
mailfloss asks HubSpot for permission to:
- read and update contacts, so it can verify addresses and apply your cleanup choice;
- read and create contact properties, so it can save each result on the contact;
- read lists, so you can choose which lists it checks;
- change email subscription status, so it can unsubscribe invalid contacts if you choose that.
Choose what mailfloss does
On the Cleanup tab, choose what happens when mailfloss finds an invalid email: wait for your OK, report it only, set a contact property your segments can exclude, unsubscribe the contact, or delete it from HubSpot.

On the Schedule tab, turn on the checks you want. All three can run at once.
- Autofloss checks every contact added since the last run, every night.
- Instafloss checks each new contact the moment it's created, through a HubSpot webhook.
- Decay Protection re-checks your existing contacts on the schedule you choose.

On the Advanced tab, add whitelist rules for addresses mailfloss should always keep, and blacklist rules for addresses it should always flag.

The Overview tab shows your latest run and every setting at a glance.

To see the contact properties mailfloss adds in HubSpot, read How to verify if the mailfloss custom properties were created in HubSpot.
Disconnect HubSpot
Open your HubSpot connection in mailfloss, go to the Advanced tab, and click Disconnect. mailfloss stops checking and changing your HubSpot contacts and removes the connection's settings. Your contacts in HubSpot are not changed.

Uninstall mailfloss from HubSpot
Disconnecting in mailfloss doesn't remove the app from HubSpot. To remove mailfloss's access to your HubSpot account:
- In HubSpot, click the settings icon and go to Integrations > Connected Apps.
- Find mailfloss, click Actions, and then click Uninstall.
- Confirm the uninstall.

If you uninstall the app in HubSpot first, mailfloss shows the connection as needing to be reconnected. Disconnect it in mailfloss to remove its settings.
For an overview of what mailfloss does for HubSpot, see the HubSpot integration page.