Every email API prices differently. Some sell monthly tiers, some bill per email, and some charge for newsletters separately. So I priced the same seven workloads on Amazon SES, Mailgun, Postmark, Resend, SendGrid and SMTPfast.
Prices come from the official pricing pages on October 6, 2026, in USD. Sources are at the bottom.
Monthly cost, cheapest first. Side project (1,000 emails): Mailgun $0 · Resend $0 · SMTPfast $0 · SES ~$0.11 · Postmark $15 · SendGrid $19.95 Early SaaS (20,000 emails): SES ~$2 · SMTPfast $19 · SendGrid $19.95 · Resend $20 · Postmark $29.50 · Mailgun $33 Growing SaaS (100,000 emails): SES ~$11 · SendGrid $34.95 · Resend $35 · SMTPfast $49 · Mailgun $75 · Postmark $115 High volume (500,000 emails): SES ~$53 · SMTPfast $349 · Resend $350 · SendGrid ~$387 · Mailgun $400 · Postmark $455 1M emails: SES ~$106 · Resend $650 · Mailgun $700 · SendGrid $733 · Postmark $775 · SMTPfast $849 Newsletter (5,000 contacts, 4 sends): SES ~$2 · SMTPfast $19 · SendGrid $25 · Postmark $29.50 · Mailgun $33 · Resend $40 Launch spike (20k plan, 60k month): SES ~$6 · Resend $29 · SMTPfast $29 · SendGrid ~$33 · Postmark ~$82 · Mailgun $105
Once you're past the free tiers, Amazon SES is the cheapest at every volume, by 3–10×. But it's raw infrastructure. Webhooks, logs and templates are yours to build. Among full email APIs, the cheapest option changes with volume: SMTPfast at 20k and 500k, SendGrid and Resend at 100k, and Resend at 1M.
How each one charges Amazon SES: $0.10 per 1,000 emails plus $0.12/GB of data. Since July 2026, new accounts default to a $0.16 plan, and you can switch back to $0.10 at any time. Mailgun: monthly tiers from $15 (10k emails). Extra emails cost $0.40–$1.80 per 1,000 depending on the tier. Postmark: monthly tiers from $15 (10k emails). Extra emails cost $1.15–$1.80 per 1,000. Resend: $20 (50k) or $35 (100k), then Scale from $90. Extra emails cost $0.46–$0.90 per 1,000 once you turn overage on. Newsletters are billed separately, per contact. SendGrid: Essentials from $19.95 (50k), Pro from $89.95 (100k, with a dedicated IP). Extra emails cost $0.47–$1.33 per 1,000. Newsletters are a separate product. SMTPfast: $9 (10k), $19 (50k) or $49 (200k), with newsletters included. Extra emails come from prepaid credits at $1 per 1,000. It runs on Amazon SES.
Free tiers Amazon SES: no free tier for new accounts since July 2026, only AWS credits ($100–200). New accounts start in a sandbox that sends 200 emails a day to verified addresses until AWS approves you. Mailgun: 100 emails a day, 1 domain, 1 day of logs. No card, but without one you can only send to 5 verified addresses. Postmark: 100 emails a month, forever. No card. Postmark approves your account manually before you can email other domains. Resend: 3,000 emails a month (100 a day), 3 domains, 30-day logs, inbound included. No card. SendGrid: no free plan since 2025, only a 60-day trial at 100 emails a day. SMTPfast: 3,000 emails a month, 1 domain, 1,000 contacts, 2 broadcasts. No card. Sending access is reviewed before you can send.
SES numbers assume about 50 KB per email and the $0.10 rate. Open "Show the math" under each one for the full calculation. Side project
Free tiers decide this one. Mailgun, Resend and SMTPfast cover it for $0. Postmark's free 100 a month doesn't, and SendGrid's trial ends after 60 days.
{% details Show the math %} Mailgun: $0. Free plan, as long as no day goes over 100 emails. Resend: $0. Free plan (3,000 a month, 100 a day). SMTPfast: $0. Free plan (3,000 a month). SES: ~$0.11. 1,000 × $0.10/1k + 0.05 GB × $0.12. Postmark: $15. Basic 10k. The free plan only covers 100. SendGrid: $19.95. Essentials 50K once the trial ends. {% enddetails %} Early SaaS
SMTPfast, SendGrid and Resend all land around $20 with room to grow to 50k. Plans that start at 10k pay overage for the second 10k.
{% details Show the math %} SES: ~$2. 20k × $0.10/1k + 1 GB × $0.12. SMTPfast: $19. Growth (50k), with unlimited domains and open/click tracking. SendGrid: $19.95. Essentials 50K. Resend: $20. Pro (50k). Postmark: $29.50. Pro 10k $16.50 + 10k × $1.30/1k. Mailgun: $33. Basic $15 + 10k × $1.80/1k. {% enddetails %} Growing SaaS
SendGrid and Resend both have a 100k tier around $35. SMTPfast's next tier jumps to 200k for $49.
{% details Show the math %} SES: ~$11. 100k × $0.10/1k + 5 GB × $0.12. SendGrid: $34.95. Essentials 100K. Shared IPs only. Resend: $35. Pro 100k. SMTPfast: $49. Scale (200k), with a 99.9% SLA. Growth plus 50k of credits would be $69. Mailgun: $75. Foundation 100k, with a dedicated IP included. Postmark: $115. Basic 125k. {% enddetails %} High volume
At 500k, SMTPfast and Resend tie at about $350. At 1M, SMTPfast becomes the most expensive here, because every email past 200k costs $1 per 1,000 in credits.
{% details Show the math %} 500,000 emails: SES: ~$53. 500k × $0.10/1k + 25 GB × $0.12. SMTPfast: $349. Scale $49 + 300k × $1/1k in credits. Resend: $350. Scale 500k. SendGrid: ~$387. Essentials 100K $34.95 + 400k × $0.88/1k. Pro 700K, with a dedicated IP, is $499. Mailgun: $400. Scale 500k. Postmark: $455. Basic 700k.
1,000,000 emails: SES: ~$106. 1M × $0.10/1k + 50 GB × $0.12. Resend: $650. Scale 1M. Mailgun: $700. Scale 1M. SendGrid: $733. Pro 700K $499 + 300k × $0.78/1k. Postmark: $775. Basic 1.5M. SMTPfast: $849. Scale $49 + 800k × $1/1k in credits. {% enddetails %} Newsletter
Only SMTPfast, SendGrid and Resend include contact lists and broadcasts. SMTPfast is the cheapest of the three because it doesn't bill newsletters as a separate product.
{% details Show the math %} SES: ~$2. Sending only. SMTPfast: $19. Growth: 25k contacts, 50k emails, 50 broadcasts. Starter covers 5,000 contacts but only 10k emails. SendGrid: $25. Marketing Campaigns Basic 10K (10k contacts, 30k emails). No automation on Basic. Postmark: $29.50. Sending only, on a broadcast stream. Same price as transactional. Mailgun: $33. Sending only. Mailgun has no broadcast product. Resend: $40. Marketing Pro, 5,000 contacts with unlimited sends. Billed separately from transactional. {% enddetails %} Launch spike