Upgrading 15.x with 4TB of Mailboxes

Question asked by kevind - 4/7/2026 at 8:29 AM

Answered

Planning to upgrade an old 15.x server to the current build. I know SmarterMail has to go through every mailbox to convert and reindex. Anyone have an estimate how long it might take to upgrade a server with 4TB of messages?

Also, wondering if the server will still work for users during the conversion process. TIA!

7 Replies

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kevind Replied

4/7/2026 at 11:49 AM

Yes, good thinking about stepped upgrade, but kind of afraid due to CVE issues.

SmarterTools, any recommendations?

J. LaDow Replied

4/7/2026 at 1:03 PM

When we did ours, we firewalled out everything but our IP that was being used for RDP to the server -- that allowed us to take run the upgrades without user connections. I think there is a "status page" that allows you to see when conversions are complete.

We noticed several things that needed reconfiguring or "initial configuring" after the upgrades as well -

It sounds like you have a much longer process ahead of you -- I almost wonder if setting up a fresh VM, fresh SmarterMail, then attaching the domains and mailboxes from the old server one by one and letting it update them would get you a more "controlled" upgrade process.

I don't know if that would be better or worse. You really may want to go ahead and get a ticket open with them - at least you've got them on the line and primed when you push the button on this --

MailEnable survivor / convert --

Zach Sylvester Replied

4/7/2026 at 8:51 PM

Employee Post

Hey Kevin,

Stepped upgrades are not needed. You should be able to just upgrade to the newest version as long as your server meets in min requirments. (At least Windows Server 2016).

If you'd like extra assistance during this processess I would recomend purchasing an installation ticket in advance so if any issues do come up support can be on the phone with you to get it handled quickly.
https://www.smartertools.com/purchase/#/add/support

Additionally support can help you prepare for the upgrade by taking a config only copy of your domains/system settings and running the upgrade in our env to make sure everything is converted properly.

Kind Regards,

Zach Sylvester

Software Developer
SmarterTools Inc.

www.smartertools.com

Rod Strumbel Replied

4/8/2026 at 6:39 AM

Which OS will make a big difference in time required and may in fact prevent the update from occurring properly. SM now runs under .NET 10. Which, older OS seem to really struggle with if even allowing it to be installed at all. Windows Server 2016 took it ok. Windows Server 2025 has some sort of issue with the installer process that takes forever while configuring the necessary windows components on a simple newer update. So... estimating time is going to be really difficult. My 10 user system on Windows Server 2025 (for testing at home) took 2 hours... my 500 domain 4000 mailbox SM Enterprise system on Windows Server 2016 took just 10 to 15 minutes. So yeah.

Tim Uzzanti Replied

4/8/2026 at 8:50 AM

Employee Post Marked As Answer

Rod,

When you say “took 2 hours,” are you referring to the installer? If so, that’s an installer issue our vendor is working to resolve. Some recent Windows updates have impacted how long Advanced Installer takes, and it’s affecting all of their customers. It occurs on other versions of Windows Server as well, but the root cause is still unknown. We’ve been sending customer logs to them for evaluation.

Beyond that, we’re noticing Windows Server 2025 is generally slower than previous OS versions. That said, it’s nice to be on the latest version, as OS upgrades can be rough.

Personally, I would still go with Windows Server 2025. If you can move to Linux, even better—lower memory footprint, better performance, and lower costs.

Tim Uzzanti

CEO

SmarterTools Inc.

www.smartertools.com

Rod Strumbel Replied

4/8/2026 at 9:22 AM

Correct Tim. It is the installer. It has been an issue since you went to .NET 9 on my system. The original FW and early .NET 8 versions didn't exhibit the issue that I recall,

I've tried it both with and without pre-uninstalling the current installation of SmarterMail before the update process, doesn't really seem to make a difference. The issue comes entirely in the analysis of, removal of, and then installation of "Windows Components" during the install process. There is a period of time during that where the progress bar goes dark... and doesn't show any sign of anything happening (literally NOTHING) for upwards of 30 minutes. Then... a slow glimmer of progress color appears, and it then slowly (very slowly) moves along.

echoDreamz Replied

4/8/2026 at 1:39 PM

We've also noticed the same with Windows Server becoming slower the last 2 releases. 2012 R2 was snappy and fast, 2016 was ok, didnt notice too many issues, 2019 also not bad, 2022 though started noticing general lack of "snappiness" even on brand new hardware. 2025 is also even worse, opening explorer is not as quick, just general use of 2025 feels sluggish.

Much like Windows 11 and its overall terrible performance.

FWIW - Cerberus FTP also uses the same installer that SM uses, it also takes quite a bit of time to do upgrades from previous versions, and it's significantly smaller than SmarterMail is.So it would appear that yes, advanced installer (maybe this version) has some issues.

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