{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'}
+;
[download]

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}