# ArrayReferenz = get_datasets( FileHandle)
sub get_datasets {
  my $handle = shift;

  my @datasets;

  # read blockwise; separate at double newline
  local $/ = "\n\n";
  while ( my $dataset = <$handle> ) {

    # remove double newline from dataset
    chomp $dataset;

    # first split by newline, then at the first ':'
    # identifiers must not contain ':' themselves
    # store splitted fields in a new hash
    my %set = map { split m{\s*:\s*}, $_, 2 } split(  m{\n}, $dataset );

    # store reference to new hash in array
    push @datasets, \%set;
  }

  # return array reference
  return \@datasets;
}

@datasets = (
          {
            'SamAccountName' => 'U011004',
            'ExpiryDate' => '19.12.2016 13:58:05',
            'PasswordLastSet' => '20.06.2016 14:58:05',
            'mail' => 'J.W@dbx.com',
            'LastLogonDate' => '20.06.2016 15:01:10'
          },
          {
            'SamAccountName' => 'U011001',
            'ExpiryDate' => '23.11.2016 08:53:28',
            'PasswordLastSet' => '25.05.2016 09:53:28',
            'mail' => 'MM.AA@yxz.de',
            'LastLogonDate' => '25.05.2016 09:53:51'
          }
        );

...
my @fields = qw( SamAccountName ExpiryDate PasswordLastSet mail );
my $format = "%-25s %-25s %-25s %-25s\n";

# header fields
printf $format, @fields;
# underline header fields (same length as header fields
printf $format, map { '-' x length $_ }  @fields;


my $datasets = get_datasets( $handle );
for my $set ( @$datasets ) {
  my %h = %$set;
  printf $format, @h{@fields};
}

SamAccountName            ExpiryDate                PasswordLastSet           mail                     
--------------            ----------                ---------------           ----                     
U011004                   19.12.2016 13:58:05       20.06.2016 14:58:05       J.W@dbx.com              
U011001                   23.11.2016 08:53:28       25.05.2016 09:53:28       MM.AA@yxz.de