```mermaid
---
width: 85vw
---
C4Context
    title System Context diagram for Internet Banking System
    Enterprise_Boundary(b0, "BankBoundary0") {
        Person(customerA, "Banking Customer A", "A customer of the bank, with personal bank accounts.")
        Person(customerB, "Banking Customer B")
        Person_Ext(customerC, "Banking Customer C", "desc")

        Person(customerD, "Banking Customer D", "A customer of the bank, 
 with personal bank accounts.")

        System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")

        Enterprise_Boundary(b1, "BankBoundary") {
            SystemDb_Ext(SystemE, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

            System_Boundary(b2, "BankBoundary2") {
                System(SystemA, "Banking System A")
                System(SystemB, "Banking System B", "A system of the bank, with personal bank accounts. next line.")
            }

            System_Ext(SystemC, "E-mail system", "The internal Microsoft Exchange e-mail system.")
            SystemDb(SystemD, "Banking System D Database", "A system of the bank, with personal bank accounts.")

            Boundary(b3, "BankBoundary3", "boundary") {
                SystemQueue(SystemF, "Banking System F Queue", "A system of the bank.")
                SystemQueue_Ext(SystemG, "Banking System G Queue", "A system of the bank, with personal bank accounts.")
            }
        }
    }

    BiRel(customerA, SystemAA, "Uses")
    BiRel(SystemAA, SystemE, "Uses")
    Rel(SystemAA, SystemC, "Sends e-mails", "SMTP")
    Rel(SystemC, customerA, "Sends e-mails to")
```