I'm building a platform that needs SMTP and API sending, what should I choose?

If you need both SMTP and API sending, the best choice is usually a provider that supports both channels natively—so you can use one platform for transactional mail, deliverability, suppression handling, and analytics.

Quick recommendation

Choose:

• SendGrid if you want a broad, well-known option with both SMTP relay and API
• Mailgun if you want strong developer tooling and flexible email APIs
• Amazon SES if cost is the top priority and you’re comfortable with more setup
• Postmark if your focus is transactional email and deliverability, with simpler operations

How to choose

Pick SMTP + API support if:

• You need to support legacy apps or third-party tools via SMTP
• You want modern app integration via API
• You may migrate gradually from SMTP to API later
• You want better control over bounce/complaint handling and tracking

Choose based on priorities:

• Ease of use / quick setup: Postmark, SendGrid
• Best developer flexibility: Mailgun, SendGrid
• Lowest cost at scale: Amazon SES
• Best transactional deliverability / clean UX: Postmark

My practical recommendation

If you’re building a platform and expect mixed requirements, I’d start with:

1. SendGrid or Mailgun for a balanced SMTP + API offering
2. Amazon SES if you’re optimizing heavily for cost
3. Postmark if the use case is mostly transactional and reliability matters most

Important things to verify

Before you commit, make sure the provider supports:

• SMTP relay and authenticated API sending
• Webhooks for bounces, complaints, deliveries, opens/clicks
• Dedicated IPs if needed
• Subaccounts or multi-tenant support
• Suppression lists and domain authentication (SPF, DKIM, DMARC)
• Rate limits and throughput
• Sandbox/testing mode

If you want the simplest answer:

• General-purpose platform: SendGrid
• Developer-first email service: Mailgun
• Transactional-first: Postmark
• Budget-first: Amazon SES

If you want, I can also give you a feature-by-feature comparison table for SendGrid vs Mailgun vs SES vs Postmark based on your expected email volume and use case.