Microsoft Exchange Pricing:
Standard Edition will have a list price of $699. For the Enterprise edition, the cost is $3,999. The Standard edition will allow five storage groups and five databases per mailbox. The Enterprise will support up to 50 storage groups and 50 databases per mailbox.
Lotus Notes Pricing
Pricing is approximately $99 per user for 1,000 users and the IBM Lotus Domino server enterprise is $137 per 1,000 users.
The pricing differences between the two makes Lotus seemingly more expensive, but with the additional features that are available, and not on Exchange, the cost will be lowered. Also if one considers the cost of the Windows OS and the CAL costs, the price difference shrinks.
Performance
The performance of Exchange 2010 is much improved from Exchange 2007. Internal mail handling is very fast. Lotus Notes, on the other hand, does not have the same performance features. Nevertheless, neither outperforms the other so much that one is a killer app over the other.