INT 16 - Shamrock Software EMAIL - CHECK FOR USER FUNCTION COMMAND-WORD
AX = 4504h
DL = port number (01h = COM1)
ES:BX -> 80-byte buffer for ASCIZ user input line
Return: AX = 4D00h if EMAIL installed on specified port
DL = flags
bit 0: user function supported (always set)
1: user entered user-function command word
if DL bit 1 set,
ES:BX buffer contains line entered by user which begins with
the defined command word and has been converted to all
caps
Note:   caller must process the returned commandline and invoke AX=4505h
within five seconds with the result of that processing
SeeAlso: AX=4505h

See also: 164503

164504 - Shamrock Software EMAIL - CHECK FOR USER FUNCTION COMMAND-WORD