I’ve got a Win2K Server with Exchange 2K running on it. We upgraded to Symantec Antivirus Corp. Ed. Ver. 10 from ver 7.  
 
Windows 2K SP4 and Exchange 2K SP3 are loaded.  
 
If a client computer open Outlook 2000 and want to view mail, then it is very slow. (Not to mention if it has a attachment) Anything from 1 min to 5 min.  
 
Please help.

Remove the scanning from the server and get the PCs to scan the mail instead..
 
Have the antivirus on exchange scan attachments or programs, but not plain text messages.. or disable the mail scanning period. Let the PCs do the work instead.