ECARGOCULT

Perl requires semicolons between (after) statements. In particular, since you haven't put a semicolon after the first line, use is thinking your hashref (HASH(0x97f5b20)) is one of its arguments (read `perldoc -f use`; it takes a LIST of arguments). You want to use that hashref as an argument to new.

{from => 'navette@mat.ensmp.fr', smtp =>'mail.materiaux.ensmp.fr'};
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constructs an anonymous hash, which should be the argument to new (the object constructor) and not to use. Just switch the second and third line:

use Mail::Sender ;
my $sender = Mail::Sender->new 
    {from => 'navette@mat.ensmp.fr', smtp =>'mail.materiaux.ensmp.fr'}
+;
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In the code above, I have also changed the indirect notation (new Mail::Sender) to direct method invocation. Indirect notation is bad practice unless you know what you do (Indirect notation will bite you if e.g. you have a new() function in the current package, or in some included module you inherit from, which is closer to the current package in the inheritance chain.)

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

use Mail::Sender;
 $sender = new Mail::Sender
  {smtp => 'mail.yourdomain.com', from => 'your@address.com'};
 $sender->MailFile({to => 'some@address.com',
  subject => 'Here is the file',
  msg => "I'm sending you the list you wanted.",
  file => 'filename.txt'});
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So the problem is that you are passing to use Mail::Sender the arguments that should go into Mail::Sender->new. When you do that, the import method of Mail::Sender which expected symbols to be imported into the caller package, tries to do that with the stringification of the hash ref you passed. And then

"HASH(0x97f5b20)" is not exported by the Mail::Sender module...
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