NPS response rate went from 6.1% to 14.3% — without touching the email
How Supportly 2×'d their NPS response rate by fixing what was invisible
Supportly sends ticket confirmations, agent replies, and NPS surveys. They had good open rates, so they thought delivery was fine. It wasn't. Half their NPS surveys were never reaching inboxes — and nobody knew.
Supportly helps customer success teams manage tickets, track response times, and measure customer satisfaction. Their own email infrastructure sends three types of high-stakes messages: ticket creation confirmations, agent reply notifications, and NPS surveys. All three need to land in inboxes for the product to function correctly. Supportly believed they were fine — their open rates looked reasonable — until they looked more carefully.
The challenge
Open rate as a false signal
Supportly's email dashboard showed a 22% open rate on NPS surveys. That seemed acceptable. But open rate is calculated as a percentage of delivered mail — if you're only delivering to 55% of recipients, a 22% open rate means 12% of your actual send list is engaging. The denominator was wrong, and nobody caught it because the provider's dashboard didn't expose inbox placement at the recipient-domain level.
Enterprise spam filters blocking support notifications
Supportly's customers are often enterprise teams with strict IT-managed email filters. Microsoft 365 and Google Workspace with enhanced security configurations were classifying Supportly's shared-IP sends as bulk commercial email. Ticket reply notifications — the most time-sensitive emails they send — were landing in Focused/Primary tabs about 60% of the time and in Promotions or Junk the rest.
No bounce-type granularity
Their previous provider classified bounces as "hard" or "soft" but didn't expose the SMTP response codes or recipient-domain signals needed to diagnose root causes. When delivery dropped at a particular enterprise domain, they had no way to trace why or act on it.
The solution
Supportly migrated all three email flows to Sendbound over a single weekend. The migration itself was straightforward; the real work came after: rebuilding their delivery monitoring using Sendbound's webhook event stream. They set up real-time alerting on bounce rate spikes by recipient domain and per-flow. Within two weeks, they discovered that a specific enterprise customer's IT team had blocklisted their previous sending domain — something they would never have found with their old tooling. They resolved it in a support call. NPS response rate climbed from 6.1% to 14.3% in eight weeks.
import Sendbound from '@sendbound/sdk';
const sb = new Sendbound({ apiKey: process.env.SENDBOUND_API_KEY });
for (const recipient of npsQueue) {
await sb.emails.send({
from: 'Supportly Feedback <feedback@supportly.io>',
to: recipient.email,
subject: 'How did we do? (30 seconds)',
template: 'nps-survey-v2',
variables: {
user_name: recipient.name,
survey_url: generateSurveyUrl(recipient.userId),
agent_name: recipient.lastAgentName,
},
tags: ['nps', `customer:${recipient.customerId}`],
// Webhook events enable per-domain delivery reporting
trackOpens: true,
trackClicks: true,
});
}"Our NPS open rate was fine — the problem was that half our sends weren't reaching inboxes. We were measuring the wrong thing and telling ourselves everything was okay. Sendbound fixed that, and our response rate doubled. It's not magic, it's infrastructure. But sometimes infrastructure is the most important thing."
The impact
The NPS improvement was the headline, but the deeper value was structural. Supportly now has complete visibility into delivery performance across every flow and every major recipient domain. They surface per-domain delivery trends to their enterprise customers as a trust signal. Their customer success team has stopped handling "I never got the ticket notification" escalations entirely.
Results at a glance
- NPS response rate from 6.1% to 14.3% — same copy, same send volume
- Per-domain delivery monitoring identified and resolved an enterprise blocklist
- "I never got the ticket notification" escalations dropped to zero
- Full delivery event stream exposed broken assumptions about open-rate math
- Enterprise customers now receive per-domain delivery reports as a trust feature
- All three email flows migrated in a single weekend with no disruption
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