SM instance from a Windows Server 2019 VM to a Windows Server 2025
Question asked by Sabatino - 9/30/2026 at 7:24 AM
Unanswered
I am preparing to migrate my SM instance from a Windows Server 2019 VM to a Windows Server 2025 VM.

While doing so, I am running tests to:
1) Enable automatic certificates (until now, I’ve used a single certificate for all domains—meaning one DNS name for SMTP, IMAP, webmail, etc.).
2) Put Spamfoo into production.

Regarding point 1, there are still a few things unclear to me, though I’ve opened a ticket and am awaiting a reply. However, I wanted to ask those of you already using it: which certificate algorithm are you using? The newer ES256 (ECDSA) or the older RS256 (RSA)? I’m not sure about the impact, having always used RS256 until now; I wonder how many clients are incompatible with ES256. One idea might be to keep the port binding certificate as RS256 while using ES256 for the SNI-based domain certificates.
That way, anyone experiencing issues can simply connect using the generic server DNS names.

As for Spamfoo, I’ve been monitoring it for over a month with a low threshold score of 2. Spot checks suggest it is accurate; I haven't found any false positives—though there are a few false negatives, which can be corrected through training.
That said, I still feel a dual-scoring system would be better—specifically, scores above 0.9 and below 0.9.
Currently, it only allows you to set a single threshold for spam vs. non-spam.
And what exactly does it consider "non-spam"? Below what score value?

For those already using it in production: what value have you set?

Regarding Windows Server 2025, I have to say the initial installation took a very long time—over 30 minutes. I had read on the forum here about slow installation times, including for updates. Is that confirmed?

I might implement secondary paths, since it seems they are now working as I expected. See https://portal.smartertools.com/community/a98172/secondary-path-again.aspx

Not so much to save money by using cheaper or slower disks, but for the benefit of faster restoration in the event of disaster recovery (read the post).
Sabatino Traini
      Chief Information Officer
Genial s.r.l. 
Martinsicuro - Italy

JerseyConnect Team Replied
So when the SSL cert feature launched it would only get ECDSA certs. We had an issue with customers doing scan to email with older copiers that didn't support ECDSA. So were using win-acme to generate a RSA cert for the port bindings. Since then they added the cert algorithm option to the UI, but it's all or nothing and not per domain, so we're still just getting the RSA cert with win-acme.
Sabatino Replied
After dealing with support tickets at SM, I’m leaning towards a hybrid approach.
I have a lot of domains, and I don't need a custom SSL for all of them. The interface is clunky because it relies on exclusion rather than inclusion, and every setting is an all-or-nothing affair.
So, I’m using centralized certificates but not the automatic generation feature. Instead, I decide which domains get an SSL—using a tool like win-acme (or Certify The Web)—and configure IIS and the domain accordingly.
Sabatino Traini
      Chief Information Officer
Genial s.r.l. 
Martinsicuro - Italy

J. LaDow Replied
@sabatino - 

We use the approach of one central certificate for the MX itself (all domains hosted use the same MX record).

The only thing we needed individual certs for is Autodiscover, and we use PoshACME to handle that automation.  It's been a pain-free approach that carried over from our MailEnable days.  The only manual step we have is to perform adding the domain initially to the list of domains we serve autodiscover for and that's it. Our scripting handles the IIS bindings and done...
MailEnable survivor / convert --
Brian Replied
So your clients can be seen in your certificate bindings?? Thats clever ;)
J. LaDow Replied
Nope --  

IMAP/SMTP/etc use a single host -- autodiscover relies on client domains (by design) -- neither are shared -- there's no enumeration of a cert to see what other domains are listed on it.


MailEnable survivor / convert --

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