In System Manager:
Expand Administrative Groups
Expand First Administrative Group
Expand Servers
Expand The server containing the Storage Groups that you want to view
Expand First Storage Group
Right click on a Storage Group and click Properties to see it's defaults
Click the Limits tab.
In Exchange 2003 there are many defaults. i.e. Global Settings, System Policy Limits, Mailbox Limits, Message Size limits, Distribution folder limits, public folder limits, Connector limits, Virtual SMTP server limits, Effective Limits and NDR limits/settings.
Out of those they are kind of scattered a bit all throughout the Exchange System manager. Here is a site that very clearly defines each setting and where they are found at. Its a great reference that I keep handy the less that I deal with '03 I start to forget some setting locations and its much easier than right clicking around everything to find the setting I am looking for.
Expand Administrative Groups
Expand First Administrative Group
Expand Servers
Expand The server containing the Storage Groups that you want to view
Expand First Storage Group
Right click on a Storage Group and click Properties to see it's defaults
Click the Limits tab.