Should I use one tool or separate broadcast and transactional?

Separate. Broadcast (ConvertKit/Buttondown) and transactional (Resend/Postmark) are different deliverability profiles; lumping them risks both.

When do I outgrow Buttondown or Kit?

Roughly when you have a recurring revenue line that depends on email-triggered sequences (post-signup onboarding, dunning, win-back) rather than just broadcast. At that point switch the lifecycle workload to Customer.io or Loops; keep the newsletter on Kit if your editorial cadence is consistent.

Does AWS SES make sense as a founder?

Only if you have engineering bandwidth and high enough volume that SES's much-lower per-email cost beats Resend / Postmark's fixed cost plus your team's time to maintain the SES stack (reputation, bounce handling, suppression). For most founders below ~500k emails/month, Resend or Postmark are cheaper once you cost your own time.

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Comparison · Marketing

Best email marketing tools for startups

Email is still the highest-ROI marketing channel for almost every founder business — but the right tool depends on which kind of email you're sending. Newsletter and creator businesses need different deliverability and editor features than SaaS lifecycle email; transactional email is its own deliverability profile entirely. Founders who lump everything onto one platform usually regret it within 18 months when one workload starts hurting another. Pick the right tool for the dominant use case at your stage; layer in a second tool for the secondary use case once volume justifies it.

By Daniel Reyes · Last updated May 21, 2026 · Editorial picks; no paid placement.

Who this is for

Founders sending broadcast newsletters, lifecycle emails, or transactional emails.

Best overall

ConvertKit (creators) / Customer.io (SaaS)

Best budget

Buttondown

Best for solo

Buttondown

The tools

ConvertKit (now Kit)

Free plan: Yes (up to 1k subscribers) · From Free, paid from $9/mo

Best for: Creator businesses, newsletters

Pros

· Built for creators
· Simple automation
· Solid free tier

Cons

· Less suited to e-commerce automation
· Reporting is basic

Customer.io

Free plan: No (paid trial) · From $100/mo

Best for: SaaS lifecycle email and triggered messages

Pros

· Powerful event-based triggers
· Multi-channel (email, SMS, push)

Cons

· Expensive at small scale
· Complex setup

Resend

Free plan: Yes · From Free, paid from $20/mo

Best for: Transactional email for developers

Pros

· Best-in-class developer experience
· Built for transactional
· Generous free tier

Cons

· Not built for broadcast marketing
· Newer (less ecosystem)

Buttondown

Free plan: Yes · From Free, paid from $9/mo

Best for: Solo newsletter authors

Pros

· Markdown-first
· Simple to use
· Indie-friendly pricing

Cons

· No advanced automation
· Limited e-commerce integrations

Frequently asked questions

Should I use one tool or separate broadcast and transactional?: Separate. Broadcast (ConvertKit/Buttondown) and transactional (Resend/Postmark) are different deliverability profiles; lumping them risks both.
When do I outgrow Buttondown or Kit?: Roughly when you have a recurring revenue line that depends on email-triggered sequences (post-signup onboarding, dunning, win-back) rather than just broadcast. At that point switch the lifecycle workload to Customer.io or Loops; keep the newsletter on Kit if your editorial cadence is consistent.
Does AWS SES make sense as a founder?: Only if you have engineering bandwidth and high enough volume that SES's much-lower per-email cost beats Resend / Postmark's fixed cost plus your team's time to maintain the SES stack (reputation, bounce handling, suppression). For most founders below ~500k emails/month, Resend or Postmark are cheaper once you cost your own time.

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Plan your first 100 customers

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