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If an order is placed by a lead - the order goes on hold.  The debtor can then be reviewed by accounts before the order is released.

You can enforce an approval process with minimum data collected before a lead can become a customer

How is a lead different to a customer?

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As you can see from the above a lead is related to a customer - so you will see many of the same fields.

Mass upload of leads

see Importing Leads, Customers, Suppliers, People and CompaniesCompanies#CreatingLeadsorDebtorswithPersonsasContacts

Creating a Lead in the system

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