Exchange Server 2003 Standard Edition is designed to meet 
the messaging and collaboration needs of small and medium 
corporations, and for specific messaging server roles or 
branch offices.
Exchange Server 2003 Enterprise Edition, designed for large 
enterprise corporations, enables you to create multiple 
storage groups and multiple databases. Exchange Server 2003 
Enterprise Edition provides a 16-terabyte message store 
that removes the constraints on the number of users and 
amount of data that a single server can manage.

But what IS the difference?



Let's take a look at the features in which both versions 
differ.

FEATURE 1: Storage Group Support
Standard Edition supports 1 storage group, and Enterprise 
Edition supports up to 4 storage groups.  Both Editions 
support the Recovery Storage Group!

FEATURE 2: Number of databases per storage group
Standard Edition supports only 1 mailbox store and 1 public 
folder store.  Enterprise Edition allows you to have 5 
databases per storage group, private or public.

FEATURE 3: Total Database Size
Now here it is absolutely vital that you realize that there 
is a huge change with SP2! 
Prior to Microsoft® Exchange Server 2003 Service Pack 2 
(SP2), there was no method to configure database size 
limits for Exchange Server 2003. Exchange Server 2003 SP2 
introduces the following new features: 


For the Standard Edition, the default configured database 
size limit will now be 18 GB, a 2 GB addition to the 
previous limit, with a new maximum size of 75 GB
For the Enterprise Edition, there is no default configured 
database size limit, and no software set maximum size.


Both versions of Exchange Server 2003 with SP2 have the 
ability to configure a limit, a warning threshold, and a 
warning interval set through registry keys.


Size check done against the database now uses logical 
database size. Empty or white space in the database does 
not count against the configured database size limit; 
therefore, no offline defragmenting is required for 
recovery exceeding the configured or licensed database 
limits.


Limit checks, done at regular intervals, are now controlled 
by the store process instead of JET. The default time 
interval is 24 hours and this interval is configurable 
through the registry. When your database size reaches the 
limit, the store will be dismounted every time the size is 
checked.  So when you mount your store, the database will 
be accessible for users, but the store will dismount again 
within 24 hours, unless you decrease the size of the store. 
Don't forget: offline defrag doesn't solve the problem 
anymore, since Exchange considers the logical database size 
now!  Cleaning is the message now :-)

To make these changes, check out the following article from 
Microsoft: Database Size Limit Configuration and Management

FEATURE 4: Exchange Server clustering
Standard Edition does not support clustering, Enterprise 
Edition does.

FEATURE 5: X.400 Connector
The X.400 connector is NOT included in the Standard 
Edition, it is included with the Enterprise Edition

FEATURE 6: The Price
No comment.

That's it...in short...the difference between standard 
edition and enterprise edition, Exchange Server 2003 SP2.

Exchange Server 2003 Standard Edition

Exchange 2003 Standard Edition is designed to meet the 
messaging and collaboration requirements of small and 
medium corporations and for specific messaging server roles 
or branch offices. 

•	One storage group can be created on a server 
•	One mailbox store database and one public folder 
store database that can be accessed by using MAPI and 
Outlook Web Access 
•	Up to four more public folder store databases that 
are accessible only programmatically 
•	Maximum 16-gigabyte (GB) database limit per 
database (75 GB with Microsoft Exchange Server 2003 Service 
Pack 2) 
•	Exchange clustering is not supported 
•	X.400 connector is not included

 Exchange Server 2003 Enterprise Edition

Exchange 2003 Enterprise Edition is designed for large 
enterprise corporations. With Exchange 2003 Enterprise 
Edition, you can create multiple storage groups and 
multiple databases. Exchange 2003 Enterprise Edition 
provides an unlimited message store that removes the 
constraints on how much data a single server can manage. 

•	Four storage groups 
•	Five databases per storage group 
•	16 terabyte database limit, limited only by 
hardware 
•	Exchange clustering is supported 
•	X.400 connector is included

Standard Edition
1.	One storage group 
2.	2 Databases max per Server 
3.	16 GB DB Size and 72 GB with SP2 
4.	x.400 connectors not included 

Enterprise Edition	
1.	Four Storage group 
2.	20 Databases 
3.	16 TB DB size limited by hardware 
4.	Clustering Supported 
5.	x.400 connectors included