If a user exceeds the numbers below, they may not have an optimized experience with their mail client/mobile device or could have errors synchronizing data.
Note, it does not matter how many days worth of e-mail a device is set to synchronize. ActiveSync has to scan the entire folder to determine which messages are within the range specified, so folders that exceed these limits can cause performance issues.
· Calendar – 10,000 items
· Contacts – 10,000 items
· Deleted items – 100,000 items
· Inbox – 100,000 items
· Sent items – 100,000 items
· Other folders created by user – 100,000
Max number of folders that can be synchronizied: 500