It's hard to tell without knowing what the receiver of the mail accepts as an "authenticated" mail/address...

(If there was a generally applicable method, every spammer would probably be interested in hearing of it :)

Update:

P.S.: if you're talking about a Gmail-internal solution, it's always good to mention it right from the start. Using two @gmail.com addresses in the sample code does not necessarily imply it — email is more than gmail...

Actually when i'm using the program given below. the program requires me to enter a password. the Email sent using this program is authenticated on the sender's side and hence is sent to the reciever's inbox rather than the Spam Folder.

  #!/usr/bin/perl
 
  use warnings;
  use Email::Send;
  use Email::Send::Gmail;
  use Email::Simple::Creator;

  my $email = Email::Simple->create(
      header => [
          From    => 'aabc@gmail.com',
          To      => 'abc@Gmail.com',
          Subject => 'Server down',
      ],
      body => 'The server is down. Start panicing.',
  );

  my $sender = Email::Send->new(
      {   mailer      => 'Gmail',
          mailer_args => [
              username => 'aabc@gmail.com',
              password => '1234qwerty',
          ]
      }
  );
  eval { $sender->send($email) };
  die "Error sending email: $@" if $@;
[download]

Ok, so?