INT 16 - Shamrock Software EMAIL - GET ELAPSED ONLINE TIME AND MAXIMUM TIME
AX = 4501h
DL = port number (01h = COM1)
Return: AX = 4D00h if EMAIL installed on specified port
BX = maximum connect time in clock ticks
CX = maximum connect time for guests (without name) in clock ticks
DX = elapsed connect time of current user in clock ticks

See also: 164500

164501 - Shamrock Software EMAIL - GET ELAPSED ONLINE TIME AND MAXIMUM TIME