It pulled in changes, pushed out updates, and made address books feel clean and reliable. Most users never heard the name “MIM”; they just searched the GAL and found the right person.
But now there is a fixed date on the calendar: MIM support ends on January 9, 2029.
- What comes next?
- How much risk sits inside those old sync rules?
And if you run multiple AD forests, those questions get louder. This article walks through what MIM really did for you and shows a clear, practical way forward.
TL;DR
- MIM’s end of support forces a decision, but copying it feature for feature is rarely the best move.
- The critical outcome for many multi forest setups is simple: people must stay easy to find and contact.
- Treat identity and access as one project (Entra ID) and contacts and calendars as another.
- CiraSync On-Premise syncs contacts and calendars across AD forests, keeps GAL searches working, and pushes contacts to phones.
- Book a CSOP demo to see how this split approach could work in your own environment.
What Microsoft Identity Manager Did for Your Organization
Microsoft Identity Manager sat between your directories and apps like a quiet traffic controller. It watched for changes, figured out what mattered, and pushed updates based on your rules.
In multi-forest AD, it gave everyone a shared, consistent view of coworkers. It created and updated users and contacts so titles, numbers, and emails stayed aligned everywhere.
It also fed Exchange so contacts and calendars reached mailboxes and then phones.
When someone joined, moved, or left, MIM pushed those updates wherever you set it to go. Most teams used it mainly for this directory plumbing, not the advanced workflow features.
Because it handled those basics, people could find and contact each other without even thinking about it.
Why Chasing a Direct MIM Replacement Can Backfire
When teams first react to MIM’s end of support, a familiar pattern kicks in.
Someone says, “We need the new MIM,” and suddenly everyone is searching for a tool that claims to handle every connector, rule, and scenario.
You end up planning another big, general-purpose identity engine.
On paper, it feels safe, but in practice, it leads to more design workshops, more custom logic, and another complex platform only a few people truly understand. The product changes, but the risk stays the same.
The real issue is that this skips a basic question: which specific outcomes do we need to protect?
For many multi-forest environments, the outcome is straightforward.
People in Forest A need to easily find and reach people in Forest B, in Outlook, and on their phones. Accurate contacts and working calendars matter more than replicating every MIM feature.
With that lens, “identity and access” becomes one trac,k and “contacts and calendars” becomes another.
You don’t have to solve everything with one massive replacement project.
How CSOP Handles Contacts and Calendars After MIM
After you peel back everything around MIM, the everyday pain looks like this:
- Can users still search the GAL and find anyone they need?
- Do phones show the right internal numbers without manual imports?
- Can teams in different forests rely on each other’s calendars?
CiraSync Server On Premise (CSOP) focuses on those questions.
CSOP connects to your existing AD and Exchange forests and builds contact sets from the sources you choose. That might be GALs, address lists, or specific groups.
It then syncs those contacts into the other forest so Outlook users can run GAL lookups across environments. You keep the familiar address book experience without trying to rebuild every MIM rule from the past.
CSOP also extends that data to where people actually work: their phones.
By writing contacts into user mailboxes, CSOP syncs contacts to mobile devices automatically. Employees open Outlook or their phone’s contact app and see the correct internal details, without another mobile app or manual CSV files.
On top of contacts, CSOP can sync calendars between two Exchange environments. That helps teams in different forests share accurate schedules and book meetings without playing email ping pong.
In this model, Entra ID can take over the long term identity and access roadmap. CSOP handles the communication layer: contacts and calendars across forests and devices. You keep people findable and reachable while you change the deeper identity stack at your own pace.
Want to see how that looks in practice? Book a CSOP demo and walk through your own AD and Exchange setup with an expert.
Conclusion
MIM has done important work for years, but it is heading toward a fixed end date. Replacing it with another “does everything” identity engine might feel safe, yet it often keeps the same complexity and risk, just with a new product name.
A cleaner approach splits the problem. Use Entra ID and related tools for identity, access, and governance.
Use CSOP to keep contacts and calendars in sync across AD forests, Outlook, and smartphones. That way, address books stay reliable, phones show the right numbers, and cross forest collaboration still works.
If you want a concrete plan instead of theory, book a CSOP demo. Bring a simple diagram of your forests, and you will see exactly how CiraSync On-Prem can handle the contact and calendar side of your post-MIM strategy.