```
C4Context
title System Context diagram for Internet Banking System
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")
System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")
Person(customerD, "Banking Customer D", "A customer of the bank, <br/> with personal bank accounts.")
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.")
}
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, with personal bank accounts.")
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")
```
