SMS is the highest-ROI marketing channel in ecommerce after email. Well-run programs produce 25-50x return on spend and contribute 10-20% of total store revenue at scale. The math is compelling once compliance and operations are handled. But the math only works when SMS is run well; sloppy SMS produces opt-outs, complaints, and legal exposure rather than revenue.
Compliance is foundational, not optional. TCPA in the US imposes $500-$1,500 fines per violation; class action exposure is real. Pre-checked opt-ins, migrating subscribers without consent records, sending without quiet hours, ignoring opt-outs — each creates existential legal risk at scale. The platform handles some compliance tooling; the operator handles the rest. There is no shortcut.
SMS is a different channel from email; treat it accordingly. Lower frequency (2-4 marketing SMS per month for most stores), stronger offers per send, time-sensitive content, conversational potential. Stores that treat SMS like an email replicator produce opt-outs and fatigue; stores that treat SMS as its own discipline produce revenue.
The platform fee is a fraction of total SMS cost. Per-message costs, carrier fees, and operator costs dwarf the platform subscription. At $1M revenue with 100K monthly messages, total monthly cost runs $5K-$10K with the platform fee being maybe 5-15% of that. Budget all layers, not just the visible one.
Bundled SMS through Klaviyo or Omnisend is the right answer for most stores under $1M. No separate platform fee, unified customer data, simpler operations. The depth that justifies Postscript or Attentive at $5M brands is unused at $500K brands. Match platform to stage.
Dedicated SMS platforms justify their cost when you use SMS-specific features. Two-way conversational commerce, keyword campaigns, sophisticated automation, advanced compliance tooling, dedicated account management — these features exist on Postscript and Attentive for reasons. When your program uses them, the premium pays back.
Two-way SMS is the differentiated capability. Customers can reply — for customer service, product questions, feedback, UGC. This is impossible in email. Stores that use SMS as a one-way blast channel miss the most differentiated use case; stores that staff two-way conversations produce experiences email cannot match.
Opt-out rate is the leading indicator. Above 1-2% per send signals fatigue, over-sending, or poor targeting. Track opt-out rate trend, not just send-by-send. Healthy SMS programs have very low and stable opt-out rates.
SMS coordinates with email; it does not replace it. Best programs use SMS for time-sensitive moments (launches, flash sales, abandoned cart recovery within minutes, post-purchase) and email for content-heavy work. Coordinated email/SMS produces more than either alone; competing email/SMS produces less than either alone.
Migration is expensive and slow. SMS platform migration involves consent records, 10DLC re-registration, flow rebuild, integration reconfiguration. Cost runs $2K-$75K+ over 4-12 weeks. Choose the initial platform carefully; switching is real work.
SMS revenue per subscriber is high but list size is harder to grow. SMS lists grow more slowly than email lists because consent requirements are stricter and customer hesitation is higher. Plan for list growth strategy as carefully as email; the program needs subscribers to send to.