Quick comparison
| Feature | SendGrid | Postmark | RelayPost |
|---|---|---|---|
| Transactional email | ✅ | ✅ | ✅ |
| Marketing/campaign email | ✅ | ❌ | ✅ |
| SMTP support | Full | Full | Full |
| REST API | ✅ | ✅ | ✅ |
| Webhooks | ✅ | ✅ | ✅ |
| Free tier | 100/day | None | 1,000/mo |
| 10K emails/mo price | $19.95/mo | $15/mo | $5/mo |
| 100K emails/mo price | $89.95/mo | ~$150/mo | $25/mo |
| Dedicated IPs | Pro plan ($89.95+) | Available | Pro plan |
| Team members | Limited by plan | Unlimited | Unlimited |
| Parent company | Twilio | ActiveCampaign | Independent |
SendGrid: the enterprise incumbent
SendGrid (now part of Twilio) is the largest email API provider. It handles both transactional and marketing email, has extensive documentation, and supports virtually every programming language.
Strengths:
- Handles both transactional and marketing email
- Massive scale — proven at billions of emails
- Extensive SDK support (Node, Python, Ruby, PHP, Go, Java, C#)
- Large ecosystem and community
Limitations:
- Complex pricing with add-ons and overages
- Shared IP pools can affect transactional deliverability
- Support quality has declined since Twilio acquisition (common complaint)
- Dashboard is cluttered and slow
- Mixing transactional and marketing requires careful IP separation
Postmark: transactional specialist
Postmark focuses exclusively on transactional email. By refusing marketing email, they keep their sending infrastructure clean and their deliverability consistently high.
Strengths:
- Best-in-class transactional deliverability
- Fast delivery times (often under 1 second)
- Clean, focused platform — no feature bloat
- Unlimited team members
- Transparent per-email pricing
Limitations:
- No marketing or campaign email — you need a second provider
- No free tier
- Smaller ecosystem than SendGrid
- Fewer SDK options
The core tradeoff
SendGrid does everything but nothing exceptionally. Postmark does one thing exceptionally but nothing else. If you need both transactional and marketing email with strong deliverability, neither is ideal on its own.
RelayPost combines both — transactional and campaign email in a single platform, with automatic separation to protect transactional deliverability. No need to manage two providers.
Pricing comparison
| Volume | SendGrid | Postmark | RelayPost |
|---|---|---|---|
| 1,000/mo | Free | $15/mo | Free |
| 10,000/mo | $19.95/mo | $15/mo | $5/mo |
| 50,000/mo | $19.95/mo | $75/mo | $25/mo |
| 100,000/mo | $89.95/mo | $150/mo | $25/mo |
When to choose each
- Choose SendGrid if you need a single platform with massive scale, extensive SDKs, and don't mind complexity
- Choose Postmark if you only send transactional email and want the best possible deliverability
- Choose RelayPost if you want both transactional and campaign email with simpler pricing and a modern developer experience
Frequently asked questions
Is Postmark better than SendGrid for transactional email?
For pure transactional email, yes. Postmark is purpose-built for transactional delivery with consistently fast delivery times and high inbox placement. SendGrid handles both transactional and marketing, which can affect transactional deliverability if not properly separated.
Is SendGrid cheaper than Postmark?
SendGrid has a more generous free tier (100 emails/day vs Postmark's paid-only model). At scale, pricing is similar — SendGrid's Pro plan starts at $89.95/month for 100K emails, while Postmark charges $1.50 per 1,000 emails ($150 for 100K). RelayPost offers 100K emails for $25/month.
Can I use SendGrid for transactional and marketing email?
Yes, SendGrid supports both. However, mixing transactional and marketing on the same account can hurt transactional deliverability. SendGrid recommends using separate subusers or IPs. Postmark avoids this by being transactional-only. RelayPost separates them automatically.
Which has better deliverability, SendGrid or Postmark?
Postmark consistently reports higher inbox placement rates for transactional email. SendGrid's deliverability varies more because their shared IP pools include marketing senders. For dedicated IPs, both perform well, but Postmark's transactional-only focus gives it an edge.
The best of both worlds
Transactional reliability + campaign support. One platform, transparent pricing.
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