use Tie::File;
tie my @adressen, 'Tie::File', 'adressen.db', recsep => "---\n"
        or die "tie adressen.db nicht moeglich: $!";
...

use IO::File;
use Tie::File;

my $fh = IO::File->new( 'adressen.db',"+>:encoding(UTF-8)" );
tie my @adressen, 'Tie::File', $fh, recsep => "---\n" or ...;

sysopen HANDLE, "./adressen.db", O_RDWR|O_CREAT or die;
binmode(HANDLE, ":encoding(utf8)");
tie my @adressen, 'Tie::File', \*HANDLE, recsep => "---\n" or die;