package MyPackage;

use strict;
use IMAP::Client;
use Config::Simple;
use Carp;

sub new { 
  my $class = shift;
  return bless {}, ref($class) || $class;
}

sub load_config {
  my $self = shift;
  $self->{'config'} = Config::Simple->new(@_);
  return $self->{'config'};
}

sub connect_to_imaphost {
  my $self = shift;
  my $config = $self->{'config'}
    or croak "ERROR : Connect to imaphost without loading config";
  $self->{'imap'} = Mail::IMAPClient->new(
    Server => $config->{'IMAP_HOST'},
    User   => $config->{'EM_UNAME'},
    ....
  );
  return $self->{'imap'};
}

# accessor functions
sub imap { return shift->{'imap'}; }
sub config { return shift->{'config'}; }

##</code><code>##

use MyPackage;
my $pkg = MyPackage->new();
$pkg->load_config('my.conf');
$pkg->connect_to_imaphost();

##</code><code>##

my $msg_count = $pkg->imap()->message_count( ... );