LibMAIL is partially based on libraries used in implementing the Courier mail server. As such, the library contains both C and C++ code; although the published API consists of C++ objects only. LibMAIL uses C++ objects declared in the mail namespace, and internally uses objects in the following namespaces:

Applications that use LibMAIL should refrain from declaring any objects in these namespaces. Applications should also refrain from declaring any C functions whose name begin with the following prefixes (these prefixes are reserved at this time):