What's the real support-response time for Postscript compared to Klaviyo when an SMS campaign breaks mid-send?

Why we are refusing the number you asked for

There is no published measurement of mid-send support response time for either vendor, and there is no dataset we could reach that would let us produce one honestly. App Store review counts measure go-to-market, not support. Anecdotes from forums are self-selected toward failure. A figure invented from our own small sample would be presented as a benchmark and used as one, which is worse than no figure.

So this page gives you the three things that are verifiable: what each vendor commits to in public, what the certification floor requires of both, and how to measure the answer for yourself before you need it.

What each vendor actually publishes

Note the asymmetry in the hours row, because it is the one that decides a live incident. Klaviyo publishes a documented weekend and peak posture. Postscript publishes weekday business hours for its compliance and approval function specifically, which is not the same desk as an outage desk and should not be read as one.

What "breaks mid-send" usually means, and who can fix it

Most mid-send failures are not platform outages, and support cannot fix the majority of them quickly because the cause is downstream.

• Carrier filtering. Messages accepted by the platform and dropped by the carrier. This is a sender-reputation and content problem. Postscript publishes that it runs "an in house carrier relations team" that "Works directly with carriers if messages get filtered" (postscript.io, September 2026). That is a capability claim, not a response-time claim, and it is the right thing to ask about in a reference call.
• Throughput queueing on a toll-free number. Not a failure at all. The send is working and arriving late. Short codes are "7x faster for SMS messages and 10x faster for MMS messages on average" (help.postscript.io, September 2026), which is why this is a number-type decision made weeks earlier, not a support ticket.
• Segment or link errors. Your own configuration. Support can help you stop the send; they cannot unsend it.
• A genuine platform incident. The rarest case, and the only one where the 30-minute critical-response criterion applies.

The practical consequence: the support-response question is the wrong question about three quarters of the time. The right question is which failures you can detect and stop yourself inside five minutes.

Measure it before you need it

This is testable during evaluation, and it costs you one week.

1. Open a real low-priority ticket with each vendor during the trial, at an awkward hour, and record the timestamp of first human reply. One data point each, honestly labelled as one data point.
2. Ask both vendors for their status page URL and read the last twelve months of incidents. Certification requires them to have one.
3. Ask in writing for the critical-incident first-response target and request it in the order form. Certification binds the vendor to Shopify, not to you.
4. Ask for two references at your send volume and ask those references one question: what happened the last time a send went wrong, and how did you find out.
5. Build your own kill switch. Know who can pause a send, from which screen, on a phone, at 9pm, without waiting for anyone.

Item five is the one that matters. A vendor that replies in fifteen minutes is still fifteen minutes of a send you could have paused in one.

When NOT to weight support responsiveness heavily

• When you send in office hours. Both vendors' documented coverage comfortably covers a weekday afternoon send.
• When nobody on your side is watching the first ten minutes of a send. Vendor response time cannot beat an unwatched dashboard.
• When the last three incidents were content or segmentation errors. Fix the pre-send checklist instead of shopping for a faster desk.