How could I hide/protect password from a Perl script

I'm writing a Perl script that needs to connect to a SMTP server in order to send a mail, but I really don't like this kind of things :

my $pass = '123456';

And I found Data::Encrypted, that should allow the user to prompt it the first time and then store it encrypted.

use Data::Encrypted file => ".passwd", qw(encrypted);
my $password = encrypted('password');

But I cannot make it work, it makes a running time error :

Bad key file format at /Library/Perl/5.12/Data/Encrypted.pm line 78

Is anybody having the same issue, or know another way to hide/protect password?