Hi Could someone please advice on using OST or PST files for following case exchange server 2010 have more than 300 remote users... n/w sometimes very bad ..Appreciate if someone can guide me through some doc that explain pros and cons of ost and pst files TIA

Hello, it'd be better to use OSTs (Outlook configured in cache mode) since you have disadvantages with PSTs like in backups (PSTs are saved locally and OSTs are just a copy of your mailbox). Greetings, Toni

Agree with Toni.. Use Ost file ( that is, enable cached mode on user machine) which will help to have offline copy of emails and also, there wont be much stress on downloading emails, becuase of only the new contents will synchronize Also, Ask the user manually archive the emails periodically and have a good backup at the server side as per your company SLA. Thank you

If you do decide to use OST's, given your n/w is sometimes very bad, dont go and turn on cache mode for everyone at once. Stage it out. Sukh

Hi, Agree with above. And I just want to make some supplements: When to use an OST or a PST: ‘An OST is the preferred method for offline storage, because it allows you to use public folders and organizational forms while you work offline. Because an OST acts as a copy of Microsoft Exchange Server-based folders, the data is backed up during the standard Microsoft Exchange Server backup procedures. NOTE: The OST is a replica. It is not a backup, and cannot be restored. A local PST must be backed up by the individual owner. One advantage a PST has is the ability to use the remote e-mail features of the Microsoft Exchange Client, download headers, move or copy messages, delete unwanted messages before downloading, and read new messages while others are downloading. When you use an OST, the synchronization process is not multi-threaded.’ For more, you can refer to the article ‘XCLN: OST and PST Quick Reference’. Hope this helps. ThanksSophia Xu