EXmerge

You will have to use filters to only extract mail between certain dates thus ensuring the size of the extracted PST is less than 2GB.

See my guide here for further information: https://www.experts-exchange.com/articles/Software/Server_Software/Email_Servers/Exchange/Export-mailboxes-using-Exmerge-and-Exchange-2003.html

Are you exporting them for use with another mail server product?  If it is another exchange product, you could always perform a move mailbox function between mail servers.

it may be easier to PST each individual user through outlook on a workstation that you can log into as each user (depends on the trust level regarding user's passwords - which you'll need to logon as them. you can always instruct them to change their password when you are done. some will, some won't care, at least in my experience), or remote into each user's workstation while they are logged on (depends on your setup). Filtering potentially several times to create what could be several PST files for each user to have to merge them seems like a lot of work when doing this for 50+ users and would definitely take longer that Outlook PST method.

good luck

I do realize you stated you couldn't do the outlook method. just wanted to point out that it may be easier if you can logon as each user is all as compared to the ExMerge method and it's 2GB limit.

its not easy to log-on more than 50 user per day or weekly i just need a tool to export all users mailbox at once whatever the size.

Exmerge will do this but you need to use filters as I said in my first post

as i understand from your first post that i will be able to export maximum 2 GB but i want to export more than 2 GB.

You did get a solution.  That's the only way to do it!
I object to the C Grade.

i set the grade according to my knowledge that i didn't solved my problem but i know that he answers me.
OK i want to change the grade.

thanks