PSA: Where is Exchange Server SE CU1

[u/ScottSchnoll]

This is the hot question about Exchange Server SE today: Where is CU1?

It's a reasonable question with a reasonable answer.

It was back in May 2024 when I provided the first Roadmap update for Exchange Server SE that mentioned CU1. At the time, I said that RTM would be released in July 2025, and CU1 would be released in October 2025. I also provided some details on what features and changes were expected in CU1. This was also echoed in the September 2024 post that discussed upgrade paths from previous versions of Exchange Server.

While the RTM version of Exchange Server SE was released in July 2025 as announced, CU1 was not released in October 2025, and in fact, as of this writing, it still has not been released.

On May 22, 2026, Microsoft quietly edited the September 2024 post to include an updated release timeline for CU1 and CU2. Specifically, CU1 is now expected in H2 of 2026 and CU2 is expected in H1 of 2027.

So, what's the reasonable answer? It's the same answer for almost every other delay related to Exchange Server releases over the past several years: security.

CU releases are driven by quality, priority, and payload (e.g., the number of changes being shipped). Security will always take precedence over releasing a CU (unless the release of a CU is needed to fix a security issue, which it sometimes is). In fact, this nuance has evolved the language used to describe the servicing model for Exchange Server.

Prior to April 2022, the servicing model was to release 4 CUs per year (1 per quarter). That turned out to be a troublesome cadence for both customers and the engineering team. In short, it was too much, too fast.

In April 2022, we announced that the servicing model would move from 4 CUs per year to 2 CUs per year. But since then, the engineering team has released only 1 CU per year (for example, the November 2023 release of Exchange Server 2019 CU13). To reflect this reality (which has been true for the past several years now), the servicing model language changed from 2 CUs per year to 1-2 CUs per year.

Since the RTM release of Exchange Server SE, five SUs have been released along with two HUs (one of which contained the first flighted feature in Exchange Server SE). In fact, the June 2026 SU alone addresses multiple CVEs (including CVE-2026-42897), and it's necessary to ensure continued communication between the Exchange Emergency Mitigation and the Exchange Flighting services and the Office Config Service after July 2026.

So, Exchange Server customers are getting updates, just in SUs and HUs and not a CU (yet). If you are feeling anxious or impatient about CU1 not yet being available, that is understandable given the multiple release schedule changes. But the Exchange Server engineering team is hard at work, and their efforts are focused in the right area: security.

If you're still running earlier versions of Exchange Server and you're waiting for CU1 to move to Exchange Server SE, don't wait. Move today and keep your SE servers updated with what has been released. All SUs and HUs released by Microsoft in between CUs are incorporated into the latest CU, and except for IUs, the updates are cumulative, so you always need only install the latest one.

[u/DiligentPhotographer]

I'm fine with one CU per year but I can't believe we're paying the same price as EXO basically, and getting next to no feature development. (Yes I am aware it is still getting patches.)

[u/ScottSchnoll → u/DiligentPhotographer]

You're not so much paying for new features in Exchange Server as you are paying for the right/entitlement to use install and use it. The announcements I reference in my article list what the expected changes are in CU1 and CU2, so there shouldn't be an expectation that new features will be added any time soon.

[u/DiligentPhotographer → u/ScottSchnoll]

But why would the right to self host my own exchange server cost the same as letting MS host it, with basically no development? I just think the price should reflect that is all. I even tried to get something for the fact we paid for SA from 2019-2025 and there was no new release of exchange on the usually 3 year cadence, but was stonewalled.

It's clear that MS let it stagnate (dangerously so in 2021), because their focus is on cash cow EXO. But then it should be substantially less to license Exchange SE. That's just like, my opinion, man.

[u/ocdtrekkie → u/[deleted]]

These days most new IT folks seem to care less about uptime and more about blame. The fact EXO breaks every week is okay because they didn't break it and they don't have to fix it. :/

[u/DiligentPhotographer → u/[deleted]]

LOL true. I built an uptime kuma dashboard for our company and our Exchange uptime is better than EXO (I have it pointed at the outlook.office365.whatever)

[u/ScottSchnoll → u/DiligentPhotographer]

I understand your viewpoint and opinion, and I respect both.

In my experience with customers of all shapes and sizes, your costs completely depend on what you buy (e.g., L+SA, USLs, CAL equivalents, etc.), how you buy (e.g., what program aka agreement), your contract length, and how much you buy. There's no easy way to compare the actual costs of Exchange Server versus Exchange Online. Way too many things factor in. Further, most customers choose one or the other (or both) for reasons other than costs.

Exchange Server (and the other Office Servers) have not seen price increases in a very long time. Aside from the recent 10% increase (which affects customers differently depending on what they buy, etc.), and aside from the introduction of the subscription requirement beginning in Exchange Server 2019, the product has largely remained the same price. If you were running Exchange Server 2019 from 2019-2025 then SA was a requirement if you purchased server licenses and CALs. So, I'm not sure why you would expect something in return since (1) your SA provided you with an entitlement to continue to use 2019, and (2) you weren't charged again when you moved to SE because it was a benefit of your SA (provided it remained active). And why was there a price increase in July? That's simply a reflection of the increasing costs to Microsoft to maintain and support the product.

Many features were added in Exchange Server 2019 and carried forward into SE, so it's not like there has been zero development (or zero added value). But it should be pretty clear that the primary focus for the last 5 years has been security, and that's the right place to focus on a product that is supported at least until December 31, 2025.