Sign in with Microsoft
Sign in or create an account.
Select a different account.
You have multiple accounts
Choose the account you want to sign in with.


The Cumulative Update 5for Microsoft Exchange Server 2019 includes an important update to the Exchange Server 2019 Sizing Calculator. Improvements are made to the logic to detect whether a design is bound by mailbox size (capacity) or throughput (IOPs), which affects the maximum number of mailboxes a database will support. Earlier versions of the calculator produced incorrect results in some situations. You’re highly recommended to use calculator version 10.4, included with the Cumulative Update 5 for Exchange Server 2019 release, to size Exchange Server 2019 deployments.


Learn about the  terminology that Microsoft uses to describe software updates.

Need more help?

Want more options?

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.

Was this information helpful?

What affected your experience?
By pressing submit, your feedback will be used to improve Microsoft products and services. Your IT admin will be able to collect this data. Privacy Statement.

Thank you for your feedback!