Most businesses track email and SMS performance by staring at a single number — usually open rate — and drawing conclusions that number was never designed to support. Real measurement means reading several metrics together as a system, because each one only tells part of the story and some of the most commonly cited numbers have become actively unreliable in recent years.
- Deliverability Metrics Come First — Nothing Else Matters Without Them
- Open Rate: Useful, But Read With Caution
- Click-Through and Click-to-Open Rate: The Content Relevance Signals
- Conversion Rate: The Metric That Actually Ties to Revenue
- List Health Metrics: The Long-Game Indicators
- SMS-Specific Metrics
- Revenue Per Recipient and Revenue Per Send
- Attributing Results Correctly Between Email and SMS
- Metrics Worth De-Prioritizing
- Building a Simple Reporting Rhythm
Deliverability Metrics Come First — Nothing Else Matters Without Them
Before evaluating engagement or conversion, confirm messages are actually reaching inboxes. Deliverability metrics are the foundation everything else sits on:
- Delivery rate — the percentage of sent messages accepted by the receiving server. A healthy program should see this well above 95%; anything lower signals list quality problems or authentication issues.
- Bounce rate — split between hard bounces (permanent, invalid addresses) and soft bounces (temporary issues). Rising hard bounce rates are an early warning that a list needs cleaning.
- Spam complaint rate — the percentage of recipients who mark a message as spam. Even a small percentage matters enormously here, since mailbox providers use complaint rate as one of the strongest signals in determining future inbox placement for the entire sending domain.
- Sender/domain reputation — trackable through tools like Google Postmaster Tools for Gmail-heavy lists, this reflects how mailbox providers view the sending domain overall, independent of any single campaign.
A campaign with excellent content but poor deliverability will underperform every time, and no amount of subject line optimization fixes an authentication or list-hygiene problem underneath it.
Open Rate: Useful, But Read With Caution
Open rate remains a commonly cited metric, but its reliability has eroded meaningfully since Apple Mail Privacy Protection began automatically pre-fetching images on Apple Mail, which can register as an “open” even when the recipient never actually looked at the message. For lists with a large share of Apple Mail users, open rate should be treated as a directional signal, not a precise measurement.
The more useful practice is comparing open rate trends over time within the same list and platform, rather than treating any single open rate number as an absolute truth, and weighting click-based metrics more heavily for lists with significant Apple Mail representation.
Click-Through and Click-to-Open Rate: The Content Relevance Signals
- Click-through rate (CTR) — the percentage of delivered messages that generated at least one click. This reflects the combined strength of subject line, timing, and content relevance.
- Click-to-open rate (CTOR) — the percentage of people who opened the message and then also clicked. Because it isolates content performance from subject-line/inbox-placement performance, CTOR is often the more diagnostic metric when open rate itself is unreliable.
A low CTR with a healthy CTOR suggests a deliverability or subject-line problem — the content works for whoever opens it, but not enough people are opening. A low CTOR despite decent opens points at a content or offer relevance problem instead. Reading these two together, rather than either alone, tells you which part of the funnel to fix.
Conversion Rate: The Metric That Actually Ties to Revenue
Conversion rate measures the percentage of recipients who completed the intended action after clicking through — a purchase, a booking, a form submission. This is the metric that should ultimately justify the program’s existence, and it is the one most businesses under-track because it requires connecting the email/SMS platform to actual outcome data, whether through a CRM integration, UTM tracking into analytics, or a shared booking system.
Without conversion tracking, a business can have excellent open and click rates and still have no idea whether the program is producing revenue. Setting this up properly — even something as simple as consistent UTM parameters feeding into an analytics platform — is worth the setup effort it takes.
List Health Metrics: The Long-Game Indicators
- List growth rate — new subscribers minus unsubscribes and removals over a given period, showing whether the list is genuinely expanding or just churning.
- Unsubscribe rate — the percentage of recipients opting out per send. A gradual creep upward is an early warning of content fatigue or frequency problems before it shows up in other metrics.
- List engagement distribution — what percentage of the list falls into active, at-risk, and dormant buckets. A healthy program keeps growing its active bucket over time; a struggling one sees dormant contacts accumulate.
SMS-Specific Metrics
SMS shares some metrics with email but has its own priorities given the channel’s directness:
- Opt-out rate — the percentage of recipients texting STOP after a given message. SMS opt-out rates should be tracked far more closely than email unsubscribes, since a spike often signals a frequency or relevance problem happening in near-real time.
- Response rate — for two-way SMS programs, the percentage of recipients who actually reply, a strong indicator of whether the channel is being used conversationally versus purely as a broadcast tool.
- Delivery rate by carrier — SMS delivery can vary by carrier, especially for unregistered or improperly registered senders; monitoring this catches carrier-level filtering issues that a blended average would hide.
Revenue Per Recipient and Revenue Per Send
Beyond conversion rate as a percentage, revenue per recipient (total revenue generated by a campaign divided by the number of recipients it reached) gives a dollar figure that translates directly into planning decisions. It lets a business compare a small, highly targeted send against a large, blended one on equal footing, since a segmented campaign to 500 relevant contacts might generate more revenue per recipient than a blast to 20,000 disengaged ones, even though the raw revenue number looks smaller.
Tracking this over time by campaign type — welcome sequence versus win-back versus promotional blast — also reveals which automations deserve more investment. A business that has never broken revenue down this way is usually surprised by which flow is actually carrying the program.
Attributing Results Correctly Between Email and SMS
When both channels run together, attribution gets murky fast — a customer who received an email and a follow-up SMS reminder before converting makes it easy to over-credit whichever channel is measured last. Where possible, use distinct UTM parameters or tracking links per channel, and when a campaign coordinates both, decide in advance how credit will be split rather than debating it after the fact when the numbers do not obviously agree. This matters most for agencies reporting results to clients, since a client comparing “email results” against “SMS results” without a consistent attribution rule will draw the wrong conclusions about where budget should go next.
Metrics Worth De-Prioritizing
Not every number a dashboard surfaces deserves equal attention. Raw open rate in isolation, total list size without an engagement qualifier, and generic industry-benchmark comparisons all tend to mislead more than they inform. A list of 50,000 mostly-dormant contacts is worth less than a list of 5,000 actively engaged ones, and comparing a niche B2B service business’s metrics against a broad e-commerce benchmark rarely produces a useful conclusion, since audience behavior varies enormously by industry and list source.
Building a Simple Reporting Rhythm
Rather than monitoring every metric constantly, a sustainable rhythm looks at deliverability and list health metrics monthly, campaign-level engagement metrics after each send, and conversion/revenue metrics on a quarterly basis tied back to overall business goals. This prevents both extremes — ignoring metrics until a problem is severe, and obsessing over every daily fluctuation in a way that produces noise rather than insight.
Frequently Asked Questions
What is considered a healthy email delivery rate?
Generally above 95%. Anything meaningfully lower points at list quality issues, authentication problems (SPF/DKIM/DMARC), or content triggering spam filters, and should be investigated before evaluating any other metric.
Is open rate still worth tracking given Apple Mail Privacy Protection?
Yes, but as a directional trend indicator rather than a precise number, especially for lists with significant Apple Mail representation. Click-based metrics like CTOR should carry more weight in the overall evaluation.
What is a good benchmark for SMS opt-out rate?
There is no single universal benchmark, since it depends heavily on message type and frequency, but a rising trend over time — regardless of the starting number — is the signal that matters most, indicating a frequency or relevance issue that needs addressing quickly.
How important is conversion rate compared to open and click rates?
It is ultimately the most important metric for justifying program investment, since it connects directly to revenue. Open and click rates are useful diagnostic signals along the way, but conversion rate is the metric that answers whether the program is working.
How often should email and SMS metrics be reviewed?
Campaign-level engagement metrics after each send, deliverability and list health metrics monthly, and conversion/revenue metrics tied to business goals on a quarterly basis is a sustainable rhythm for most programs.
Terry has 30+ years in software and SEO. He’s the founder of Salterra Digital Services and SEO Spring Training, host of the Roundtable SEO Mastermind, and lead instructor at SEO University — teaching the exact tactics his team uses on client work.
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