What email backend should I use if I need inbound replies too?

If you need inbound replies — meaning people can email your app and you receive/process those emails — you want an email backend that supports both sending and receiving.

Good options:

Best all-around choices

• SendGrid

  • Easy to set up
  • Supports inbound parse/webhooks for receiving emails
  • Good docs and common in production systems

• Mailgun

  • Strong inbound email support
  • Very good for parsing incoming messages
  • Often a top choice when inbound email matters

Also possible

• AWS SES
  • Excellent deliverability and cost
  • Supports inbound email, but setup is more complex
  • Good if you already use AWS

If you only need replies forwarded to your app

• Postmark
  • Great for outbound transactional email
  • Inbound support exists, but it’s not always the first choice if inbound is a major requirement

Recommendation

• If inbound replies are important, I’d usually recommend Mailgun or SendGrid.
• If you want lowest cost / AWS-native, use SES.
• If your app is mostly transactional email and inbound is secondary, Postmark is excellent.

If you want, I can also give you:

1. a feature comparison table, or
2. the best choice for your stack (Node/Python/Rails/etc.).