A supplier who quoted everything for two years stops replying. No falling out, no complaint — the last two RFQs just went unanswered.
Before you assume anything, it's worth knowing this almost always has a boring explanation.
The five reasons, roughly in order of likelihood
The person left. You were emailing an individual, and that individual changed roles or companies. Your RFQ is landing in an inbox nobody reads. This is by far the most common cause and the easiest to miss, because nothing bounces.
They're at capacity. A shop that's full doesn't always say so. Quoting work they can't take costs them time, so quotes to newer or smaller customers quietly drop down the list.
Your work stopped fitting. They've moved up in part size, bought different equipment, or changed their minimum order. Your parts are now awkward for them and they haven't wanted to say it.
You've become expensive to quote. If they've quoted eleven jobs and won one, you're a poor return on their estimator's time. This is invisible to you and completely rational for them.
Something did go wrong. A payment dispute, a rejected batch, a conversation with someone else at your company that you never heard about.
Only the last of those is a relationship going bad, and it's the least likely.
How to find out, in one message
Don't send another RFQ. Send a short, direct question to a human, ideally by phone:
We've sent a couple of RFQs recently and haven't heard back — has something changed at your end? Happy either way, just want to know whether to keep sending them.
That works because it gives them an easy exit. A supplier at capacity, or one who's outgrown your work, will usually tell you honestly if you make it costless to say so. One who simply lost your emails will be surprised — and you'll find out the contact left.
What doesn't work: another RFQ with "just following up" on it. That's the fourth thing they've ignored, and it makes the silence harder to break.
Then fix the structural cause
If the contact left, the useful lesson isn't about that supplier — it's that your RFQs go to one person at every supplier you use. All of those relationships have the same single point of failure, and you'll hit it again.
Two things reduce it:
Have a second name at every supplier you use regularly. Ask before you need it. It's a normal thing to ask.
Send RFQs to the company, not the individual, wherever the way you send them supports it. Anything that lets more than one person at their end see the request removes the failure mode entirely.
The number that would have told you sooner
"They've gone quiet" arrives as a surprise because response rate isn't a number anyone keeps. It's a feeling, and feelings lag by months.
If you track one thing per supplier, make it how many of the last ten RFQs they quoted. A supplier who's gone from ten out of ten to four out of ten hasn't gone silent yet — but that's the moment to ask, while it's still a conversation rather than a replacement.
When to actually move on
If they tell you the work no longer fits, believe them and thank them. That's a supplier being honest at a small cost to themselves, and worth remembering when your parts change.
If you get nothing after a direct question to a named person, treat them as unavailable rather than lost. Keep them on the list, stop counting on them, and requalify a replacement before you need one urgently.
The mistake is the middle path: keep sending RFQs into silence, keep half-expecting a quote, and find out on the job where you needed three numbers and got two.