BPM - track and send message based on input message

Hi All,

I have simple bpm to receive two files, merge and create output file.

Start -- Receive1 -- Receive2 -- Transformation -- Send -- Stop.

Scenario is working good as expected, now I need to build the controls. I setup a timeout parameter for 1 min for the block. If File1 is available but NOT File2, after 1 min, bpm is terminated, but I need to send an email stating that File2 doesn't exist at the input folder. How do I track the message2 in BPM whether it exists or not and send an email.

Thanks for your help.

thanks..Hari