Yes you can. Softalk Share Server version 1.0.4 and above has an offline feature, which is available from within Outlook. You can choose which of your folders you wish to take offline by selecting File | Offline Settings from the Outlook menu. You can then work offline by selecting File | Work Offline from the Outlook menu. The first time you do this, Outlook will take a few minutes to create the offline store (depending upon the amount of data you have chosen to take offline). Subsequent times will be much quicker since only changes will be synchronized.
Once you are working offline, you may make changes to the contents of the folders you have chosen to take offline. When you next work online, by selecting File | Work Online, these changes will be synchronized with the online store.
While working offline you will only have access to your personal folders that you have chosen to take offline. You will not have access to public or shared data.