This is the ONLY Blat Command Line parameter that has to be in a particular order. It MUST be the first parameter after the Blat command!
Specify the text file to use for the Message Body of the message you are sending. You may need to put the full path to the file like this c:\path\msgfile.txt.
Note: this is a text file, not a .doc file, or .xls file or other binary type file. It can be .html if you also use the -html parameter.
If you use the "-" character instead of a filename, Blat will be looking for the Message Body on STDIN (like the keyboard, or a redirect, as expected - ^Z ends the input) or specified with the -body parameter.