Help on single instance store and hard link linux

[Marco]

Hello Cyrus users,

  I'm wonder about mails deduplication. I don't know hard link on  
linux, maybe you could help me to understand.

I run 2.4.17-Invoca-RPM-2.4.17-6.el6 on Red Hat Enterprise Linux  
Server release 6.3 with singleinstancestore: 1.

I send one mail to 1200 recipients in a single session (one queueid of  
Postfix).
Then I go to fs and I list (ls -l) the email received by an account.
  I would read a value of 1200 on ls -l. Instead I read a very lower  
value, such as 161:

-rw------- 161 cyrus mail   117838 Mar 27 15:19 2253.


I'm a bit confused about Postfix lmtp_destination_concurrency_limit  
and lmtp_destination_recipient_limit. Now they are:

lmtp_destination_concurrency_limit = 20
lmtp_destination_recipient_limit = 300

How can I set these limits to take benefit from mail deduplications?

I also read this experience:

http://docs.kolab.org/en-US/Kolab_Groupware/3.0/html/Administrator_Guide/chap-Administrator_Guide-Tweaking_Tips_for_Cyrus_IMAP.html#sect-Administrator_Guide-Tweaking_Tips_for_Cyrus_IMAP-Speeding_Up_Authentication

Should I rise both limits to 1200?

Thanks a lot
Marco