Can one customer pay for another customer's transactions using lockbox?

Yes, if you have set up a relationship between these customers, or if the Allow payment of unrelated transactions system option is enabled for this lockbox submission. The paying customer should be identified by a customer or MICR number on the receipt record.

Otherwise, if you're using AutoMatch when applying a receipt from Customer A to a transaction from Customer B, the receipt is designated as paid by Customer B. Additionally, all transactions listed to be paid by one receipt must belong to the same customer, otherwise lockbox imports the receipts as Unapplied.

If the Allow payment of unrelated transactions system option isn't enabled, you must set up a relationship between the customers before you can make applications in this way.