We're an early-stage startup. what's the cheapest reliable email API?

Determining the "cheapest reliable" email API depends on whether you are sending transactional emails (password resets, notifications, receipts) or cold outreach/marketing.

1. The Absolute Cheapest Raw Infrastructure: Amazon SES

• Cost: $0.10 per 1,000 emails (or $1 per 10,000 emails).
• Free Tier: 3,000 emails/month free for the first 12 months if hosted on AWS.
• Reliability: Built on Amazon's global infrastructure; industry-leading deliverability and uptime if domain records (SPF, DKIM, DMARC) are configured correctly.
• The Catch: It is strictly unmanaged infrastructure. You get no visual template editors, minimal logs out-of-the-box, and a plain interface. Setup requires managing AWS IAM permissions and sandbox approval.
• Best For: Developers who want near-zero email bills and don't mind handling email setup in code.

2. Best Developer Experience & Free Tier: Resend

• Cost: $20/month for up to 50,000 emails ($0.40 per 1,000 above that).
• Free Tier: 3,000 emails/month (100 emails/day) forever.
• Reliability: Excellent. Built on modern infrastructure, native React Email support, fast delivery, and clear log tracking.
• The Catch: Strictly for transactional/product-driven email. Not built for cold outreach or bulk marketing.
• Best For: Modern web stacks (Next.js, React, Node.js, Python) where fast implementation and clean UI matter as much as low price.

3. Best Cheap All-In-One (Transactional + Marketing): Brevo

• Cost: Pay-as-you-go or $9/month for 5,000–10,000 emails.
• Free Tier: 300 emails/day (~9,000/month) forever.
• Reliability: EU-based, high deliverability, built-in CRM, and template builder.
• The Catch: Daily cap on the free plan (300/day) means you can't blast large lists all at once on the free plan.
• Best For: Early-stage teams needing transactional APIs alongside email marketing, newsletter tools, or CRM features in one subscription.

Key Comparison

Provider	Starting Price	Monthly Cost (50,000 emails)	Free Tier	Best Feature
Amazon SES	$0.10 / 1,000	~$5.00	3,000/mo (AWS)	Lowest raw price on earth
Resend	$20/month	$20.00	3,000/mo	Modern dev experience & React Email
Mailtrap	$15/month	$20.00	4,000/mo	Deliverability monitoring + dev testing
Brevo	$9/month	~$56.00	300/day (~9k/mo)	Transactional + Marketing/CRM hybrid
Postmark	$15/month	$55.00	100/mo (Dev Plan)	Fastest speed & highest delivery guarantee

Summary Recommendation

1. If you have developer bandwidth: Start with Amazon SES. Nothing beats $0.10/1,000 emails.
2. If you want instant setup and high-quality SDKs: Pick Resend. The $20 tier gives you 50,000 emails with zero DevOps overhead.
3. Important Note: Do not use transactional APIs (SES, Resend, Postmark) for cold outreach; doing so risks immediate account suspension. For cold outreach, look into tools specifically built for mailbox warmup and cold sending (e.g., Instantly or Lemlist).