Our Enterprise+ plan is the one for our largest enterprise customers -- the extra features are:

- Antivirus scanning for attachments

- IP access controls

- Custom tables (an advanced feature where you can create your own record schema and link the records to canonical records in our product -- for example you can create a table of "customers" and link each feature to the customers that want it)

- Account backup (obviously we do our own backups, but this feature lets you easily dump your whole account to JSON so you can do your own backups too)

- Some advanced features around managing licenses within your organization

- Our concierge service (which includes support for security/operational reviews plus some sessions to guide you in rolling out our product within your organization)