Dear poor reader who ran a search with the term “is there a limit on how many delegates you can have in outlook 2003 when using rpc over http” and ended up at my site:
The answer is yes.
Microsoft recommends you have no more than 4 delegates. They only tested Outlook with 4 delegates and you can expect to have major issues opening the delegates tab when you have anything over 7 delegates.
Also, keep in mind that delegates counts against your 32kb rule limitations, so if the user has a lot of rules and a lot of delegates, they may have a lot of squirrely issues.
As a general rule, you only need to set up a delegate when a user needs to “send on behalf” of you. If they need to add/remove events from your calendar or see items in other folders, it’s best to just grant them straight up sharing permissions to the data (right-click on the folder, choose Sharing).