Use Latest Build as Gateway to v15?

Question asked by kevind - 2/10/2026 at 12:41 PM

Unanswered

Still have a server running ver. 15 that we're planning to upgrade, but not for a few months. Wondering if it's possible to use the Jan-30 Build as an incoming gateway to legacy 15.x? Seems like we've run into a SMTPUTF8 issue in the past. Anyone doing this? TIA!

4 Replies

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Kayasidh Kasyapanun Replied

2/11/2026 at 12:37 AM

Have the same problem here.

Douglas Foster Replied

2/12/2026 at 8:01 AM

Assuming that internal users are trusted, the solution is to hide the weak server fromall external access.

Remote users would have to log into a VPN or other remote access interface. No more emote EAS for cell phones, EWS for MacBooks, or MAPI for Outlook on laptops. Painful but safe.

Then add an inbound gateway using current SM or other product to prevent attacks using SMTP.. Should probably add an outbound gateway as well, but that seems slightly less critical

I strongly believe in using an inbound gateway and doing your inbound spam filtering before it reaches your main server. So that part of the change should be permanent.

kevind Replied

2/12/2026 at 10:25 AM

@Douglas, yes, we're hiding the weak server from public access. But my question is whether Build 9526 will work as an "incoming gateway" for version 15. We tried it like a year ago with an older build and there were issues with SMTPUTF8 delivery.

Douglas Foster Replied

2/12/2026 at 11:58 AM

Ah, yes. Outside my experience. Forum has been quiet on that topic , so I expect yes. If you have support, that is your best source

If you have Linux experience in-house, Postfix is worth considering. Lots of products plug into it, including Declude Reboot. I have only studied the documentation. It is an impressive free product, but with a non-trivial learning curve

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