Mailgun vs Postmark
Mailgun is the flexible general-purpose email API supporting transactional and bulk sending. Postmark is the transactional-only specialist with best-in-class inbox placement. Here is the full comparison.
Key takeaways
Mailgun handles both transactional and bulk email from one API — Foundation at $35/month (50k), Scale at $90/month (100k). Postmark handles transactional only and charges a premium for its deliverability specialisation — $15/month (10k), $50/month (50k), $100/month (100k). Postmark is cheaper under 10k emails/month. Mailgun is cheaper above 50k. The choice is flexibility vs deliverability purity.
- Mailgun: Foundation $35/month (50k emails), Scale $90/month (100k), $0.80/1,000 overages. Dedicated IPs: +$35/month.
- Postmark: $15/month (10k emails), $50/month (50k), $100/month (100k). Postmark's Flex plan doubled to $2/1,000 in Dec 2025.
- Postmark refuses bulk and marketing email — transactional only. Mailgun accepts both. Postmark accounts are terminated for mass campaigns.
- Postmark's dedicated transactional IP pools never mix marketing sends — the structural reason its inbox placement is consistently higher.
Mailgun vs Postmark: Quick Comparison
| Features | Mailgun | Postmark |
|---|---|---|
| Email types allowed | Transactional + bulk + marketing | Transactional only |
| At 10k emails/month | $35/month (Foundation) | $15/month |
| At 50k emails/month | $35/month (Foundation) | $50/month |
| At 100k emails/month | $90/month (Scale) | $100/month |
| Dedicated transactional IPs | ✓ extra cost | Included (shared transactional) |
| Message streams | No | Yes |
| Email validation API | Yes | No |
| Inbound email parsing | Yes | Yes |
| EU data residency | Yes (EU region) | No |
| Message retention | Short default (varies by plan) | 45 days full content |
What Are Mailgun and Postmark?
Mailgun
A developer-focused general-purpose email API supporting transactional, bulk, and marketing sending with email validation, inbound parsing, and EU data hosting.
- Foundation: $35/month for 50,000 emails. Scale: $90/month for 100,000. Overages: $0.80 per 1,000 above plan volume.
- Flex plan doubled to $2 per 1,000 emails in December 2025 — now less competitive at very low volumes
- Supports transactional, bulk, and marketing email. No restrictions on email type or recipient relationship.
- Email validation API, inbound email parsing, send-time optimisation, A/B testing, and EU data residency (EU region)
- Owned by Sinch. Dedicated IPs available at +$35/month. Strong API documentation and broad SDK coverage.
Postmark
A transactional-only email API that refuses bulk and marketing email, maintaining pristine IP pools used exclusively for application-triggered sending.
- Pricing: $15/month (10k emails), $50/month (50k), $100/month (100k), $200/month (300k)
- Flex pay-as-you-go plan: $2/1,000 emails (doubled in December 2025) — only useful at very low test volumes
- Strictly transactional: accounts sending bulk campaigns or mass marketing email are terminated, not warned
- Message streams: separate outbound transactional (account activity) from broadcast (newsletters) into isolated IP-reputation streams
- 45-day full message retention on all plans — full content and event history retained much longer than Mailgun's defaults
Pricing Models: Mailgun, Postmark, and mailtani
Mailgun: monthly flat by volume, Flex pay-as-you-go now more expensive
- Foundation: $35/month for 50,000 emails + $0.80/1,000 overages
- Scale: $90/month for 100,000 emails + dedicated IPs, advanced analytics
- Flex: $2 per 1,000 emails (doubled in December 2025) — previously $1/1,000
- Dedicated IPs: +$35/month per IP
- EU region: same pricing, data stored in European data centres
Postmark: monthly flat, premium for deliverability specialisation
- $15/month for 10,000 emails
- $50/month for 50,000 emails
- $100/month for 100,000 emails
- Flex: $2/1,000 emails (doubled December 2025) — only viable for very low test volumes
- No free tier. 45-day full message and event retention on all plans.
mailtani: €89 once, use Mailgun or Postmark as your SMTP backend
- One-time €89 payment — no monthly fee, no per-email charges beyond your SMTP provider cost
- Connect Mailgun or Postmark SMTP credentials as the sending backend
- Postmark at 10k/month: $15. mailtani marketing layer: €0/month ongoing.
- Full marketing layer — sequences, warmup, broadcasts, rotation — included in one-time payment
Mailgun vs Postmark: The Full Breakdown
Postmark's deliverability advantage is structural, not marginal. By refusing to allow marketing or bulk email on its infrastructure, Postmark maintains dedicated IP pools that ISPs exclusively associate with high-quality, permission-based application email. When a password reset lands in the inbox instead of spam, that is in part because Postmark's sending reputation has never been contaminated by a poorly-received campaign. Mailgun mixes transactional and bulk traffic on shared infrastructure — the deliverability is good, but the structural purity that makes Postmark's transactional performance consistent is absent.
Mailgun's flexibility is its primary advantage. If your application sends transactional emails and you also want to run bulk announcement campaigns or marketing newsletters from the same API, Mailgun supports all of it. Postmark will terminate your account for sending mass campaigns. For SaaS products with varied email needs — user notifications, product updates, marketing sequences — Mailgun's single-API breadth reduces complexity and the number of providers to manage.
Message streams are a Postmark feature with no Mailgun equivalent. Postmark lets you create separate outbound transactional and broadcast streams, each with its own sending IP pool and deliverability reputation. A newsletter campaign that generates higher spam complaint rates cannot damage the deliverability of your account's transactional stream — they are isolated. This protection matters at scale when your product's most critical emails (two-factor auth codes, payment receipts) share an account with lower-priority broadcast traffic.
Pricing crossover makes each tool cheaper at different volume bands. Under 10,000 emails per month, Postmark at $15/month is cheaper than Mailgun Foundation at $35/month — making Postmark the default for small-volume SaaS apps just starting out. Between 10k and 50k emails, Mailgun is cheaper. Above 50k/month, Mailgun Foundation at $35/month covers the same volume Postmark charges $50/month for. The Mailgun Flex plan price doubled in December 2025 to $2/1,000, removing it as a cost-effective low-volume option.
Neither tool covers marketing sequences or warmup. Both Mailgun and Postmark are transactional infrastructure only. Founders who need marketing email on top of their transactional setup end up using both an API and a separate marketing tool. The combined monthly cost of Mailgun Foundation plus a basic marketing tool often runs $60-150/month every month. Using Mailgun or Postmark SMTP with mailtani as a one-time €89 payment achieves the same full-stack outcome at near-infrastructure cost ongoing.
How Mailgun, Postmark, and mailtani Compare, Feature by Feature
| Feature | Mailgun | Postmark | mailtani |
|---|---|---|---|
| Bulk / marketing email allowed | |||
| Transactional-only IP pools | |||
| Message streams separation | |||
| Inbound email parsing | |||
| Email validation API | |||
| EU data residency option | |||
| Send-time optimisation | |||
| A/B testing | |||
| 45-day full message retention | |||
| Dedicated IPs available | |||
| Webhook events | |||
| Email templates | |||
| SMTP relay supported | |||
| Marketing sequences / warmup | |||
| Campaign editor | |||
| Flat one-time pricing | |||
| No ongoing monthly platform fee | |||
| Best transactional deliverability | |||
| Broader API use cases | |||
| Sinch ecosystem integrations |
The Third Option: Why Founders Pick mailtani
- Connect Mailgun or Postmark as your SMTP backend and run marketing sequences, warmup, and broadcasts on top — one-time €89 payment, no ongoing platform fee
- Use Postmark for critical transactional email (password resets, receipts) and mailtani for marketing sequences — best of both worlds
- Founders and SaaS builders on tight budgets get professional email infrastructure without monthly SaaS fees on top of their SMTP cost
- The BYOS model means you own your sending domain reputation entirely and can switch infrastructure without migrating marketing tooling
What Each Tool Is Built For
Mailgun
Optimised for developers and teams who need a flexible email API covering transactional, bulk, and marketing sending from one platform.
Mailgun is the right choice when your application sends multiple types of email and you want one API to handle all of them. Transactional notifications, bulk announcements, marketing newsletters — Mailgun supports all without the restrictions Postmark imposes. Email validation, inbound parsing, A/B testing, and EU data residency make it a versatile infrastructure tool for SaaS products with varied email requirements. The trade-off: by mixing transactional and bulk traffic on shared infrastructure, Mailgun cannot offer Postmark's level of transactional-only deliverability purity.
Postmark
Optimised for applications where inbox placement for password resets, receipts, and critical notifications is non-negotiable.
Postmark is the right choice when your most important emails must reach the inbox every single time. By refusing to send marketing or bulk email, Postmark ensures its IP pools are exclusively associated with high-quality, opted-in application email — the structural reason its transactional deliverability is consistently best-in-class. Message streams add a second layer of protection by isolating transactional and broadcast reputation from each other. For SaaS apps where a missed password reset or payment receipt is a support ticket and a churn risk, Postmark's specialisation is worth the premium over Mailgun.
Mailgun vs Postmark: Who Should Choose Which?
Choose Mailgun if...
- You send both transactional and bulk or marketing email and want one API to handle all types
- You send above 50,000 emails per month where Mailgun Foundation is cheaper than Postmark
- You need email validation, inbound email parsing, or send-time optimisation alongside transactional sending
- You need EU data residency for compliance and data localisation requirements
- You want A/B testing on your transactional email content without a second tool
Choose Postmark if...
- Inbox placement for password resets, payment receipts, and account notifications is non-negotiable
- You want dedicated transactional-only IP pools that never share reputation with bulk campaigns
- You want message stream separation to isolate transactional and broadcast deliverability reputation
- Your sending volume is under 10,000 emails per month where Postmark is cheaper than Mailgun
- You want 45-day full message retention for debugging and compliance without extra cost
Mailgun vs Postmark: Pros & Cons
Mailgun
Pros
- Supports all email types — transactional, bulk, and marketing from one API; no restrictions on email type or recipient relationship
- Cheaper at 50k+ volumes — Foundation at $35/month covers 50k; Postmark charges $50/month for the same volume
- Email validation API — verify email addresses before sending to reduce bounces; absent in Postmark
- EU data residency — EU region option for data compliance requirements; Postmark has no equivalent
- A/B testing and send-time optimisation — optimise transactional email performance; not available in Postmark
Cons
- Mixed-use IP reputation — transactional and bulk traffic share infrastructure; lower deliverability purity than Postmark's transactional-only pools
- No message streams — cannot isolate transactional and broadcast reputation within one account; Postmark does this natively
- Flex plan doubled — Flex pay-as-you-go went from $1/1,000 to $2/1,000 in December 2025; less competitive at low test volumes
- Shorter message retention — default event and content retention shorter than Postmark's 45-day full content retention
- No marketing sequences — like Postmark, no campaign editor or sequence builder; requires a second tool for marketing email
Postmark
Pros
- Best-in-class transactional deliverability — dedicated transactional-only IP pools; never contaminated by bulk or marketing sends
- Message streams — isolate transactional and broadcast IP reputation within one account; unique Postmark feature
- 45-day full message retention — full email content and event history retained on all plans; best debugging and compliance retention
- Cheaper under 10k/month — $15/month vs Mailgun Foundation's $35/month for low-volume transactional SaaS apps
- Strict focus keeps reputation pristine — refusing bulk senders means Postmark's shared pools stay consistently clean
Cons
- Transactional only — no bulk campaigns, no marketing email; account terminated if rules violated
- More expensive 10k-100k — $50/month at 50k vs Mailgun Foundation at $35/month for the same volume
- No email validation — no built-in API to verify addresses before sending; Mailgun includes this
- No EU data residency — no data localisation option; Mailgun offers an EU region
- No A/B testing or send-time optimisation — Mailgun has both; Postmark focuses purely on delivery, not analytics features
Neither Mailgun nor Postmark right for you?
Mailgun and Postmark are infrastructure only — neither gives you sequences, warmup, or a campaign editor. mailtani does: bring your own SMTP key (Mailgun, Postmark, or SES) and add a full marketing layer on top. €89 once, no monthly platform fees on top of your SMTP cost.
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