Just at first glance, you have '$_' when you mean "$_" - note the double quotes instead of the single ones. Single quotes mean "as is", while double quotes man "interpolate variables". Another thing I see, which may or may not be a problem, is that by the time you get to the sendmail() command, you only have the last line of bas.txt. Perhaps you want to replace the while loop with something like:

$txt = <RES>;
print $txt;
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-- Dan