buildText {
#blabla
return ($out, $text_mail );
}

sendMail {
my $p = { @_ };
my $body = $p->{body};  
my $text_mail = $p->{text_mail};  
#blabla
}

main_function {
#blabla
my ($body, $text_mail) = buildText();
return sendMail(
body => $body,
text_mail => $text_mail);