Request on Exchange Server SE CU1 Codebase and Trial Version Behavior

hi Mahmood20​  here you go

1.Exchange Server Subscription Edition (SE) CU1 vs. Exchange 2019 CU15

Is SE CU1 a standalone codebase or a continuation of Exchange 2019 CU15?

Answer:
Exchange Server SE CU1 is a direct continuation of Exchange Server 2019 CU15.

• Exchange SE RTM (released October 2022) was code-identical to Exchange 2019 CU15.
• Exchange SE CU1 (May 2023) builds on that baseline, introducing new features and updates that are only available in SE (not backported to 2019 CU16 or later—since there are no further 2019 CUs).
• Microsoft has forked development at CU15: Exchange 2019 has effectively ended major feature updates; SE is now the active codebase.

Summary:

Exchange SE CU1 = Exchange 2019 CU15 + New Features.
It’s not a clean rewrite—just a subscription-bound evolution of 2019.

2.What happens when the Exchange SE Trial expires?

The Exchange Server SE trial is 180 days. Here's what happens when it expires:

Functionality After Expiration:

• All core server functionality continues to operate.
• Mail flow, mailbox access, calendaring, and OWA/ECP still work.
• No artificial block is introduced that brings the server down or stops services.

However:

• The server will be in an unlicensed state, and you may:
• See warnings in the admin interface, event logs, and PowerShell.
• Be non-compliant with Microsoft licensing terms.
• Some cumulative updates or support might be restricted if you're unlicensed (from a Microsoft support contract point of view).

Server usability:

The server remains usable after trial expiration, but it's not legally licensed for production use.

Suggested Actions:

If you're using the SE trial and intend to continue:

• Convert to a fully licensed SE install by purchasing the appropriate subscription licenses via Volume Licensing or CSP.
• Use PowerShell to activate:

Set-ExchangeServer -Identity "YourServerName" -ProductKey XXXXX-XXXXX-XXXXX-XXXXX-XXXXX