INT 92 - Da Vinci eMail Dispatcher - "NetOpen"
        AX = E105h
        BX = 0007h
        CX:DX -> parameter block (see below)
Return: AX = 0000h Error
        AX = handle
Note:   this function is used to open a submission channel

Format of parameter block:
Offset  Size    Description
 00h    WORD    operation (1 = read, 2 = write)
 02h    WORD    segment of uppercase To: username
 04h    WORD    offset of uppercase To: username
 06h    WORD    segment of "DVSEMAIL"
 08h    WORD    offset of "DVSEMAIL"
 0Ah    WORD    segment of node address
 0Ch    WORD    offset of node address