The headline numbers, and why they mislead
The line everyone repeats: SMS open rates are around 98%; email open rates are around 22%. Both numbers are roughly accurate. Both numbers are also roughly useless for deciding which channel to send your review requests on.
Open rate is the wrong metric. The metric you actually care about is review-completion rate — what fraction of requests turn into a posted review on Google, Yelp, or wherever. By that metric the gap narrows considerably, and for some business types it inverts.
What follows is the real picture: completion rates by channel, the cost picture (10DLC fees, per-message costs, TCPA compliance), and the right answer for each common business type. Then the "best of both" pattern that consistently outperforms either channel alone.
Conversion: what the funnel actually looks like
For a typical local service business, the post-service review request funnel looks roughly like this:
SMS, 30 minutes after service:
- 98% delivered
- 95% opened (within 3 minutes for the median customer)
- 35-45% click the link
- 60-75% of clickers complete a public review
- Net: ~25-35% of requests become posted reviews
Email, sent the next morning:
- 95-99% delivered (good list hygiene)
- 22-28% opened
- 8-12% click the link
- 50-65% of clickers complete a public review
- Net: ~5-8% of requests become posted reviews
So SMS wins on completion rate by roughly 4-5x for the typical service business. The 5x advantage is real — but it is a lot smaller than the 5x open-rate gap suggests, because SMS click rates and email click rates are not as far apart as the open-rate numbers imply, and email completion-given-click is actually slightly higher (people are at a desk, easier to type).
For some business types those numbers are closer or even reversed, which is the next section.
Where email beats SMS
There are three business contexts where email outperforms SMS for review requests, and the logic is the same in each: the customer relationship runs through email already, so an email feels appropriate where a text would feel intrusive.
- B2B and professional services. Lawyers, accountants, consultants, agencies — the engagement runs on email throughout. SMS for the review request reads as off-brand. Email lands as a natural extension of the relationship.
- Multi-day or multi-visit engagements. Construction projects, dental treatment plans, real-estate transactions where service "ends" gradually rather than at a single moment. SMS is built around an immediate trigger; email handles the "thank you for the whole engagement" framing better.
- Older demographics or any customer base where a meaningful percentage do not have a mobile number on file. Force-fitting SMS where you do not have permission or a number creates a worse experience than email.
For everything else — restaurants, salons, plumbers, HVAC, dentists, auto shops, gyms — SMS at the 30-minute mark is the right primary channel. The vertical-specific patterns are in the plumbers landing page, the restaurants page, and the auto-repair page.
The 10DLC and TCPA compliance picture
Sending business SMS in the US is meaningfully more regulated than it was three years ago. Two compliance regimes apply:
10DLC (10-Digit Long Code) registration. As of 2023, every US business sending SMS through a 10-digit long code has to register with The Campaign Registry. Registration involves identifying the business, describing the use case, and accepting per-message and per-month fees from the carriers (T-Mobile, AT&T, Verizon). Costs:
- Brand registration: $4 one-time fee
- Campaign registration: $10 one-time + $1.50–$10/month per campaign depending on use case
- Per-message carrier fees: roughly $0.003–$0.005 per outbound message in addition to your SMS provider's base rate
- Total cost for a small business sending 1,000 review requests/month: roughly $0.04–$0.08 per message all-in, including provider fees
If you skip 10DLC registration, your messages get filtered or dropped at the carrier level. Your provider may also pass through penalties.
TCPA (Telephone Consumer Protection Act). The federal law governing business-to-consumer messaging. Two rules matter for review requests:
- You need prior express consent to send marketing SMS. "Marketing" is interpreted broadly. A review request is generally treated as transactional rather than marketing if it is tied to a completed service the customer just received — but the safer pattern is to capture explicit opt-in at booking ("we may text you about your appointment, including a review request after service") and store the timestamp.
- You must include an opt-out path in the message itself ("Reply STOP to unsubscribe") and honor it immediately.
Statutory damages for TCPA violations are $500–$1,500 per text. A class action over 10,000 unconsented texts can exceed $5M. Most SMS providers handle the opt-out plumbing automatically, but the consent capture is your job.
Email is regulated under CAN-SPAM, which is a weaker regime — required opt-out, no false headers, accurate from line. The compliance burden is lower than SMS by an order of magnitude.
The cost picture, side by side
For a 200-customer-per-month single-location service business:
SMS-only (10DLC registered):
- 200 messages/month × ~$0.05/message = $10/month in messaging costs
- + $1.50–$10/month campaign fee
- + your SMS provider's base rate
- Total messaging cost: roughly $15–$30/month plus the review tool subscription
Email-only:
- 200 messages/month through any modern transactional provider (Resend, Postmark, SendGrid)
- All-in cost: roughly $0–$5/month at this volume
- Plus the review tool subscription
The cost difference is real but small in absolute terms. At review-tool-subscription scale ($30–$80/mo for the tool), adding $15-$30 for SMS to capture 4-5x the review volume is straightforwardly worth it for service businesses where SMS is the right primary channel.
The "best of both" pattern that outperforms either alone
The single highest-converting setup is not picking SMS or email — it is using both, with each serving the role it is best at:
- SMS as the primary trigger, 30 minutes after service. This is your conversion engine. Most reviews come from this message.
- Email as the fallback, 48 hours later, for non-responders only. A short, plain-text email — no fancy design — that thanks the customer by name and offers the link again. Plain text outperforms HTML for this single use case because it reads as personal rather than marketing.
- No third reminder. Two touches is the right number. A third reminder is desperation and converts worse than no reminder.
This pattern recovers roughly 30-40% of the SMS non-responders into completed reviews via the email fallback. Net completion rate ends up around 35-45% for the request as a whole — a meaningful step up from SMS alone.
The mechanic that powers this is per-customer trigger automation, not batched campaigns. If your tool sends "every Friday's review requests in one batch," you have lost the timing advantage on both channels. The how-it-works page walks through the per-customer trigger pattern in detail.
What to do today
If you are sending review requests via email only: add SMS as the primary, keep email as the fallback. The conversion lift is large enough that it pays for the 10DLC registration in the first month.
If you are sending via SMS only: add the 48-hour email fallback. You are leaving 30-40% of recoverable conversions on the table.
If you are sending via either channel on a weekly batched cadence: switch to per-customer trigger timing. Same number of messages, much higher completion rate.
If you are not sending at all: start with SMS to your last 50 completed customers as a manual test. The data will tell you within a week whether the conversion claim holds for your specific customer base. In our experience, it always does.
This post was originally published at https://getsignalroute.com/blog/sms-vs-email-review-requests.
