Re: Proxy ---->FIle---> Mail creation after the successfull creation of file.

Try this

Proxy -- > PI -- > FTP (Use a operating command to create a trigger file after messge processing)

FTP--> PI--> Mail

(Read a trigger file)

Single flow

Use Maintain Order at runtime and create 1st reciver as FTP and 2nd as Mail

Proxy  ------->  FTP

           --------> Mail

Use Maintain Order at runetime.

I have not tried this but it just come to my mind this can be one more approach.