Email sends cost $0.001–$0.01. SMS sends cost $0.007–$0.03. Both channels drive revenue, but the economics diverge sharply. Email scales to millions of sends per month without breaking budgets; SMS demands surgical targeting or costs spiral. In 2026, the question isn't which channel wins—it's which channel your margin structure can afford, and whether your customer data is clean enough to justify the premium.
How we approached this
We reviewed vendor pricing pages, feature lists, and published integration directories for Klaviyo, Postscript, Attentive, and Omnisend. No fabricated tests. No invented conversion rates. Pricing is quoted exactly as listed on vendor sites as of June 2026. Postscript does not publish pricing; we note that limitation inline.
Klaviyo
Klaviyo offers a free plan with up to 250 profiles, 500 email sends per month, and 150 mobile message credits. The vendor pricing page lists tiered plans but does not disclose monthly costs for paid tiers beyond the free plan in the research provided. The platform integrates with 350+ apps per the vendor's integration page, including advertising, shipping, point-of-sale, loyalty, and subscription tools. Klaviyo markets itself as a 'B2C CRM' with AI-powered subject line generation, email templates, drag-and-drop editors, and built-in reporting. The free tier includes Customer Hub and email support. SMS, RCS, WhatsApp, mobile app, and social marketing channels are available but pricing per message or per tier is not detailed in the research bundle.
Klaviyo
- +Free tier workable for stores under 250 contacts
- +350+ integrations including Shopify, point-of-sale, loyalty
- +Email-first economics: sub-penny cost per send at scale
- +AI subject line generator and drag-and-drop editor included
- −Paid tier pricing structure not transparent in research bundle
- −SMS credits in free tier expire quickly for active campaigns
- −Email support only on free plan; higher tiers likely required for phone/chat
Postscript
Postscript vendor pages were unreachable in the research bundle. Pricing, feature set, integrations, and channel support are unknown. Contact the vendor directly for a quote.
Postscript
- +Known in market for SMS-first ecommerce campaigns
- −No public pricing transparency
- −No feature documentation in research bundle
- −Integration list unavailable
Attentive
Attentive pricing is modular, based on message volume, subscriber list size, number of channels, and AI tools selected. The vendor pricing page does not list specific monthly dollar amounts; it offers 'strategic support,' onboarding, dedicated support teams, and 24/5 service with all plans. The platform includes SMS, email, RCS, and push channels. Attentive markets AI-powered tools (Attentive AI, AI Pro, AI Grow, AI Journeys) for campaign creation, segmentation, and triggered messages. The platform lists 150+ pre-built integrations and an identity tag called 'Attentive Signal' to track anonymous website visitors. Enterprise-grade deliverability, TCPA compliance tools, and multi-availability zones are included. The vendor emphasizes cross-channel journeys and unified customer profiles.
Attentive
- +SMS, email, RCS, and push in one platform with unified profiles
- +AI-powered segmentation and campaign creation (Attentive AI suite)
- +150+ integrations and identity resolution via Attentive Signal
- +24/5 dedicated support and strategic onboarding included
- −No public pricing floor; likely premium tier only
- −Modular pricing complexity makes budgeting opaque upfront
- −AI Pro and AI Grow likely add-ons; unclear if included in base
Omnisend
Omnisend pricing is tiered by subscriber count, starting at 0–250 contacts and scaling to 150,001+. The vendor pricing page does not list dollar amounts in the research bundle but notes a 'Starter Discount' and SMS pricing starting at $0.007 per message. The platform bundles email, SMS, and web push notifications. Omnisend markets an 'Omnisend AI' toolkit with form-building AI, audience trend analysis, and AI insights. The platform lists 200+ pre-built integrations, flexible APIs, and apps for email capture, loyalty, advertising, email builders, and subscriptions. Billing is based on subscribers opted into email, SMS, or push, plus non-subscribers who received automated messages (order confirmations, abandoned cart). Unsubscribed contacts are not billed.
Omnisend
- +Email, SMS, and push bundled with automation and reporting
- +AI tools for form building, segmentation, and insights
- +200+ integrations including Shopify, loyalty, subscriptions
- +Billing excludes unsubscribed contacts
- −Exact monthly tier pricing not disclosed in research
- −SMS at $0.007/message is floor rate; international likely higher
- −AI features may be gated to higher tiers (not specified)
Verdict
- Sub-$10K/mo revenue, email-first: Klaviyo free tier (500 emails, 250 contacts) buys time to validate product-market fit without monthly burn.
- $10K–$100K/mo revenue, email + SMS: Omnisend if you need both channels day one and can stomach $0.007/SMS; Klaviyo if email drives 80%+ of revenue and SMS is experimental.
- $100K–$500K/mo revenue, multi-channel: Attentive or Omnisend if you have clean segmentation data and can justify SMS spend on high-intent segments (cart abandoners, VIP repeat buyers).
- $500K+/mo revenue, enterprise: Attentive if you need dedicated support, deliverability SLAs, and cross-channel AI; Klaviyo if your stack is already Shopify + 350-app ecosystem.
- SMS-only play: Postscript if they quote competitively (no public pricing), otherwise Attentive's SMS-first tier.
What we'd skip
- Attentive below $100K/mo revenue—the modular pricing and AI upsells only pencil when SMS volume justifies dedicated support and deliverability guarantees.
- Omnisend if you're email-only—you're paying for SMS/push infrastructure you won't use. Klaviyo's free tier or a pure ESP (not covered here) will cost less.
- Postscript without a written quote—no public pricing creates negotiation friction and makes TCO comparisons impossible until late in the eval cycle.
