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Head-to-head · Transactional Email Software

Postmark vs Retarus Transactional Email

  • Updated Sep 2026
  • Both researched from official sources
  • 3 checks side by side
Higher score Postmark #2 in Transactional Email Software 8.6/10 Free plan · paid from $15/mo Free plan✓ 1 of 2 features Visit Postmark
Retarus Transactional Email #8 in Transactional Email Software 6.8/10 Pricing on request ✓ 2 of 2 features Visit Retarus

Postmark leads on 1 check, Retarus Transactional Email on 1, and 1 is even. Who comes out ahead on the 3 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scorePostmark · 8.6/10
  • Free planonly Postmark
  • Most featuresRetarus Transactional Email · 2 of 2

Postmark scores higher on our rubric for transactional email software: 8.6 against 6.8 out of 10; our editors rank them #2 and #8.

Postmark offers free plan; Retarus Transactional Email doesn't publish it. Retarus Transactional Email offers event webhooks; Postmark doesn't publish it.

Postmark is the better fit for teams prioritizing message-stream separation. Retarus Transactional Email is the better fit for enterprise teams needing compliance-oriented delivery.

  • Postmark fits best

    Teams prioritizing message-stream separation

  • Retarus Transactional Email fits best

    Enterprise teams needing compliance-oriented delivery

Advertiser disclosure: iTechGuides is reader-supported. We may earn a commission when you click some links. It never changes our verdict. How we rank.

Side by side

Feature Postmark 8.6/10 Visit ↗ Retarus Transactional Email 6.8/10 Visit ↗
At a glance
Editor score 8.6 6.8
Ranking #2 in Transactional Email Software #8 in Transactional Email Software
Best for Teams prioritizing message-stream separation Enterprise teams needing compliance-oriented delivery
Pricing model Free plan + paid Paid
Starting price $15/mo Not published
Free plan ✓ (best) Not published
Free trial — —
Deployment Cloud Cloud, Browser extension
Platforms Web Web
Support Live chat, Docs Phone, Docs
Compliance GDPR, 2FA GDPR, HIPAA, PCI DSS
Integrations 12 integrations 4 integrations
Built for Solo, Small business, Mid-market, Enterprise Enterprise, Mid-market
Features Postmark 1/2 · Retarus Transactional Email 2/2
Event webhooks Not published ✓ (best)
Dedicated IP option ✓ ✓
Specs
Delivery methods Not published Both
Template options Not published Not published
Delivery log retention Not published Not published
Monthly send limit 10000 emails/mo Not published
Our review
Pros
  • Separate transactional and broadcast message streams
  • REST API, SMTP sending, inbound parsing, and event webhooks
  • Reusable templates with previews, variables, and test sends
  • Supports both REST API and SMTP delivery methods
  • Includes callbacks, webhooks, monitoring, and delivery reporting
  • Offers enforced TLS, dedicated IPs, and enterprise integrations
Cons
  • Free plan allows only 100 emails per month
  • Free plan does not allow overages
  • Advanced inbound processing starts with the Pro plan
  • Contact-sales pricing makes budget comparison less direct
  • Delivery-log retention varies between monitoring and reporting functions
  • The enterprise focus may exceed the needs of simpler sending programs
Our verdict

Postmark is an email delivery service for application teams sending transactional and broadcast messages through REST APIs or SMTP. It supports web and API access, official libraries for multiple programming languages and frameworks,…

Read the review →

Retarus Transactional Email is an enterprise service for sending high-volume transactional messages from business applications. It supports REST API and SMTP delivery, making it suitable for teams connecting modern applications,…

Read the review →
  1. PostmarkTransactional Email Software 8.6Free plan · paid from $15/mo
  2. Retarus Transactional EmailTransactional Email Software 6.8Pricing on request

Strengths and trade-offs

  • Postmark — where it wins

    • Separate transactional and broadcast message streams
    • REST API, SMTP sending, inbound parsing, and event webhooks
    • Reusable templates with previews, variables, and test sends

    Where it doesn't

    • Free plan allows only 100 emails per month
    • Free plan does not allow overages
    • Advanced inbound processing starts with the Pro plan

  • Retarus Transactional Email — where it wins

    • Supports both REST API and SMTP delivery methods
    • Includes callbacks, webhooks, monitoring, and delivery reporting
    • Offers enforced TLS, dedicated IPs, and enterprise integrations

    Where it doesn't

    • Contact-sales pricing makes budget comparison less direct
    • Delivery-log retention varies between monitoring and reporting functions
    • The enterprise focus may exceed the needs of simpler sending programs
  • Postmark8.6/10 · Free plan · paid from $15/mo

    A focused email delivery service for teams separating transactional and broadcast traffic.

    Visit PostmarkFull verdict →
  • Retarus Transactional Email6.8/10 · Pricing on request

    A compliance-oriented delivery service for complex enterprise messaging environments.

    Visit RetarusFull verdict →

More comparisons

All transactional email software comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Sep 2026

Last updated · How we research and update