Can some one please let me know on below 2 things
1. If i enable auditing on UserMailboxes and SharedMailboxes for let say 90 days. These logs will also count against mailbox size? if yes then what is the best method to retain these logs without eatng much Mailbox storage?
No, they count to the RecoverableItems quota (which is 30GB by default, 100GB for mailboxes on hold).