Email Relay for The Excel Group

The Excel Group's order management system had been sending emails without incident for years. Then it just stopped. Orders were still coming in, but they couldn't send the confirmation emails, the shipping notifications, or any of the other messages that kept their customers or suppliers in the loop. We came in to figure out what happened and put it right without blowing up the budget.

Technology Stack

Two problems hiding behind each other

The diagnosis turned up two compounding issues. First: Microsoft had finally and completely dropped support for TLS 1.0, an outdated security protocol, for sending emails. Their order management system was old enough that it only knew how to speak TLS 1.0—so every email it tried to send was being rejected.

Second: because their office doesn’t have a static IP address, the IP they happened to be assigned at the time was on the Spamhaus blocklist. Even if the TLS problem had been fixed, delivery would still have been unreliable.

Either issue alone would have been enough to kill email delivery. Together they made it nearly impossible to diagnose from the outside, since the symptoms looked the same regardless of which one was the cause.

A $12,000 fix wasn't the right answer

The straightforward solution would have been to upgrade to the latest release of their order management system. But the quote for that came in somewhere north of $12,000.

For the owner—who is a few years out from retirement and running a lean operation— that kind of spend on a system that otherwise works fine didn’t make sense. The goal wasn’t to modernize the OMS. The goal was to get emails flowing again.

A small solution that does exactly one thing

We built a lightweight Ruby SMTP relay server that runs in a Docker container on the Synology NAS we had previously set up for them—hardware they already owned, already running in their office.

The OMS sends email exactly the way it always has, to a local address that it can still reach. The relay picks it up, hands it off to Postmark using a modern TLS connection and a properly authenticated sending domain, and Postmark delivers it. The dynamic IP problem disappears entirely because outbound mail never touches their office IP.

The relay does one thing, and it does it well. It’s a simple, focused solution that restores email delivery without the need for a costly upgrade or a major change to their existing workflow.

"Everything seems to be working properly now, thank goodness! I can't believe how much I've accomplished today now that we're back up, much more than expected. Thank you for prioritizing us and taking such good care of us!" Greg Tudor, Owner of The Excel Group