Four Easy Steps
Configure the old system to host the desired users by creating accounts, setting up email domains, and configuring any necessary email protocols, like IMAP or POP3.
Configure Zimbra to host the desired users by creating accounts, setting up email domains, and configuring necessary email protocols, like SMTP or webmail access.
Route incoming email traffic to the appropriate system based on the target user's email address or other specifications.
Train users on how to access their email on the appropriate system and ensure they have the necessary login credentials.
SYSTEM MONITORING
Monitor both systems to ensure that email messages are being sent and received properly and that users are not experiencing any issues accessing their email. It may be helpful to enlist the help of an IT professional to assist with these steps or provide specific guidance based on the systems in use.
We manage the complexity of user data transfer without interrupting your business operations. Our team also monitors system performance during migration to ensure emails are sent and received properly without affecting user access.
Our architecture ensures all users receive mail correctly, regardless of their current system (Old or Zimbra). Continuous monitoring helps prevent delivery issues and ensures smooth communication across both environments with expert support when required.
Situations like how do host some users on my old system and some on zimbra service usually come up during transitions. Rarely planned perfectly from the start. One part of the business is ready to move, another still depends on the old setup. What typically happens is teams try a split approach. Keep things running as they are, while gradually shifting users. It sounds simple, but dependencies show up quickly. Mail flow, access control, data consistency. Small gaps, but they matter. In practice, this leads to a series of connected decisions. How long should both systems run together. What needs to sync, what doesn’t. Where risks are acceptable, and where they are not. Most businesses end up revisiting surrounding layers. Not everything needs to change immediately. But clarity across systems becomes necessary, especially as more users move.
Some teams come in right at the start of a transition. Others, midway through when things feel a bit uneven. We’ve worked with organisations balancing old and new systems longer than expected. Not always by choice. Sometimes because certain users or processes can’t move yet. There are IT teams deeply involved in every step. There are also cases where the internal team just wants validation before making the next move. A few engagements stay short. Just enough to stabilise things. Others continue quietly until the transition is complete, or at least manageable.
Yes, but don't call it "magic"—it’s Internal Mail Routing. You set one server (usually the new Zimbra box) as the Primary MX. If a mail hits Zimbra and the user doesn't exist there, the server doesn't "Bounce" it; it "Relays" it to the old legacy IP. It’s a ₹0 logic fix, but if you misconfigure the Local Delivery settings, the two servers will just keep passing the email back and forth until the "Hop Count" expires. We’ve seen ₹5 Lakh ($5,425) projects stall because of a single "Looping" error.
This is the biggest pain point. Zimbra users won't automatically "see" the Legacy users in their contact list. You have to manually sync them or use a Distributed GAL. If you don't, your CEO will complain that they "can't find" the floor manager in the directory. At JIL, we handle the LDAP synchronization so the two systems "talk" to each other. It’s a one-time setup fee of roughly ₹8,500 ($92), but it saves you from a thousand "Why is he not in my contacts?" tickets.
If you aren't careful, yes. The Legacy server might see the "Relayed" mail from Zimbra and think it’s a Spoofing attack because the IP doesn't match the original sender. You have to Whitelist the Zimbra IP on your old system. In 2026, SPF and DKIM are ruthless. If your "Return-Path" doesn't align, your internal emails will end up in the "Junk" folder. We audit your SPF Records to include both IPs, ensuring your internal communication doesn't trigger a "Deceptive Site" warning.
That’s the whole point of this setup. It’s a Phased Migration. You move 10 users today, test the "Calendar Sharing," and if it works, you move the rest next month. It protects your "Uptime." If you tried a "Big Bang" migration and it failed, your whole office would be dark. By splitting the domain, you cap your risk. If a ₹12,000 ($130) migration goes sideways, it only affects the "Test Group," not the entire company.
Usually, no. Not out of the box. Zimbra won't know if a Legacy user is "Busy" in an Outlook 2010 calendar. If your company relies heavily on Meeting Invites, you need to move "Teams" together, not individuals. Keep the "Sales Team" on one server and "HR" on the other. If you mix them, your scheduling will be a disaster. We advise clients to treat the split as a "Transition State," not a permanent home. Use it to save on licensing for 6 months, then finish the move.
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