Short answer: it depends on what you mean by “cheapest” (per‑subscriber vs per‑email), how technical you are, and what features you need. Quick recommendations by use case:
- Lowest monetary cost if you don’t mind technical setup: Amazon SES (very low cost per email) + a lightweight sending/automation frontend (self‑hosted like Mailtrain, Mautic, or a small app that uses SES). Cheapest at scale but requires ops/maintenance.
- Lowest effort + cheapest for moderate size/use: Brevo (formerly Sendinblue) — pricing is based on emails sent, not on subscriber count, so it’s often cheaper for growing lists that send infrequently. Good free tier and straightforward UX.
- Balanced, easy to use with a generous free tier: MailerLite — user‑friendly, good automations and landing pages, often cheaper than Mailchimp as you grow.
- Writer/publisher focused (simple, often free to start): Substack or Buttondown — easy for newsletters that are mainly paid/unpaid subscriptions; Substack takes a revenue cut for paid newsletters, Buttondown is small and inexpensive.
- Cheapest with no third‑party limits if you want full control: self‑hosted sending + SES/Postfix/etc. Lowest ongoing cost but highest maintenance.
Factors to consider
- Pricing model: per‑subscriber vs per‑email vs revenue share vs flat tiers. If you send infrequently to a big list, per‑email can be cheaper.
- Deliverability: cheapest services sometimes have poorer deliverability. SES + good warmup is excellent for cost/deliverability, but needs care.
- Features you need: automations, segmentation, landing pages, sign‑up forms, templates, analytics, integrations, GDPR/consent tools.
- Technical overhead: self‑hosting saves money but requires maintenance and handling bounces/unsubscribes.
- Growth curve: if you’ll scale fast, pick a provider with predictable pricing and good deliverability.
Short decision guide
- Non‑technical, want low effort: try Brevo or MailerLite.
- Writer/patron model: Substack (if fine with revenue share) or Buttondown.
- Technical and cost‑sensitive at scale: Amazon SES + self‑hosted/small app.
- Want simplest handoff and features (paid marketing): consider paid tiers of MailerLite or ConvertKit (more expensive but feature rich).
If you tell me: approximate current list size, expected monthly send volume, how often you email, and whether you want to manage infrastructure, I’ll give a specific recommendation and a rough cost comparison for the next 6–12 months.