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Email Marketing · head to head

Resend vs Sailthru

Resend logo

Resend

Email Marketing

Email API for developers to send transactional and marketing email

From
Free
Rated
-
Full reviewWebsite
Sailthru logo

Sailthru

Email Marketing

Retail and publisher email personalisation, now one product inside the Marigold portfolio

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Resend has a free tier, so it costs nothing to try first.
  • Each has a real cost: Resend free tier is capped at 100 emails per day, which is restrictive for apps with bursty transactional volume.; Sailthru the product sits in a portfolio with several overlapping platforms under one owner, so roadmap investment is a portfolio decision rather than a product decision and is worth asking about in writing.
  • They diverge on capability: Resend covers Email API and SDKs, Sailthru covers Interest profiles.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Resend and Sailthru actually diverge.

Attributes where Resend and Sailthru differ
AttributeResendSailthru
Starting priceFreeOn request
Pricing modelfreemiumquote
Free tierYesNo
Platformsweb, apiWeb, REST API

Identical on both: user rating (Not yet rated), category (Email Marketing).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Resend

  • Email API and SDKs
  • Domain management
  • Audience and contacts
  • Automation workflows
  • Email analytics
  • Dedicated IPs

Only in Sailthru

  • Interest profiles
  • Personalisation engine
  • Prediction Manager
  • Site personalisation
  • Zephyr templating
  • Lifecycle optimiser

What people use each for

The jobs each tool is most often brought in to do.

Resend

  • Sending transactional emails from a web appnot Sailthru
  • Running marketing email campaigns to contact listsnot Sailthru
  • Automating onboarding or lifecycle email sequencesnot Sailthru
  • Tracking deliverability and engagement analyticsnot Sailthru

Sailthru

  • A publisher sending a personalised daily newsletter assembled per reader from a content cataloguenot Resend
  • A retailer that wants email and on-site recommendations driven by the same affinity modelnot Resend
  • High-cadence sending where per-recipient content assembly matters more than journey branchingnot Resend
  • Teams that want churn and lifetime value scores available as native campaign conditions rather than imported fieldsnot Resend

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Resend

  • Free tier is capped at 100 emails per day, which is restrictive for apps with bursty transactional volume.
  • Marketing and transactional plans are billed and priced separately, so a product needing both must budget for two tiers.
  • Dedicated IPs are only available on the Scale plan and require a minimum daily send volume.

Sailthru

  • The product sits in a portfolio with several overlapping platforms under one owner, so roadmap investment is a portfolio decision rather than a product decision and is worth asking about in writing.
  • Pricing counts stored profiles, so retained inactive readers keep costing money long after they stopped opening anything.
  • On-site personalisation requires a developer to implement the JavaScript and maintain the content feed, which puts the highest-value feature behind engineering time.
  • Zephyr is a proprietary templating language, so template maintenance skills are scarce compared with the Liquid syntax used by most competitors.
  • It is built for high-cadence content and retail sending, and B2B lifecycle programmes with long sales cycles sit poorly on the model.

Pricing, plan by plan

Resend

Free
  • FreeFree
    • 3,000 emails/month
    • 100 emails/day
    • 3 domains
  • Pro$20/month
    • 50,000 emails/month
    • 10 domains
    • 100 AI credits/month
  • Scale$90/month
    • 100,000 emails/month
    • 1,000 domains
    • Slack and ticket support

Sailthru

On request
  • Sailthru$undefined/year
    • Priced on stored profiles and send volume
    • Site personalisation and prediction features licensed by module
    • Annual contract through Marigold

Which should you pick?

Choose Resend if

  • You need email api and sdks.
  • You want to start without paying.
  • You work on web, api.
  • You also want domain management.
Resend review

Choose Sailthru if

  • You need interest profiles.
  • You work on Web, REST API.
  • You also want personalisation engine.
Sailthru review

Questions people ask

Is Resend or Sailthru better?
Neither clearly leads. Resend starts at Free and Sailthru at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Resend or Sailthru?
Resend has a free tier; the other does not. Paid plans start at Free for Resend and On request for Sailthru.
Does Resend or Sailthru run on more platforms?
Resend runs on web, api. Sailthru runs on Web, REST API.
Can I use Resend for free?
Yes. Resend has a free tier, so you can try it without paying. Sailthru starts at On request.
What is Resend best used for?
Resend is most often used for sending transactional emails from a web app, running marketing email campaigns to contact lists, automating onboarding or lifecycle email sequences, tracking deliverability and engagement analytics. Of those, sending transactional emails from a web app and running marketing email campaigns to contact lists are not what Sailthru is typically brought in for.
What can Resend do that Sailthru cannot?
Resend covers Email API and SDKs, Domain management, Audience and contacts, Automation workflows. Sailthru covers Interest profiles, Personalisation engine, Prediction Manager, Site personalisation.

Answered from the vendors’ own pages

Resend: What does Resend cost?

Transactional email starts free for 3,000 emails/month, then Pro is $20/month for 50,000 emails and Scale ranges from $90 to $1,150/month for up to 2.5M emails. Marketing email is priced separately by contact count, starting free for 1,000 contacts.

Source
Sailthru: Who owns Sailthru now?

Marigold, formerly CM Group, which also owns Campaign Monitor, Emma, Selligent, Liveclicker and Cheetah Digital.

Resend: Is there a free plan, and what are its limits?

Yes, the free transactional plan allows 3,000 emails per month capped at 100 per day across 3 domains, and the free marketing plan allows up to 1,000 contacts.

Source
Sailthru: Does that affect the roadmap?

It can. Overlapping products in one portfolio compete for investment, so ask which platform is the strategic one for your segment before signing multi-year.

Resend: How is usage metered?

Transactional plans are metered by number of emails sent, with overage billed per 1,000 emails. Marketing plans are metered by number of contacts rather than emails sent.

Source
Sailthru: Is it worth it just for newsletters?

For personalised daily newsletters at publisher scale it remains one of the strongest options. For simple broadcast sending it is heavily over-specified.

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