use strict;
my $str = 'Something above
-----Message d\'origine-----
De : Myself <myself@himself.com>
Envoyé : vendredi 8 mars 2019 14:30
À : Someone <someone@himself.com>
Cc : AnotherGuy <another@himself.com>
Objet : My bad I forgot how to do it
Hi,
blabla';
my $regex = qr/-----Message d'origine-----.*(?:\r?\n(?!\r?\n).*)*\s*/mp;
my $subst = '';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html