Mailgun deliverability problems, alternatives?

If you’re having deliverability problems with Mailgun, the right alternative depends on what kind of email you send:

Best alternatives by use case

1) Transactional email at scale

Good for password resets, receipts, alerts, verification emails.

• Postmark – often the top choice for deliverability and simplicity
• Amazon SES – very low cost, powerful, but more setup/ops
• SendGrid – feature-rich, broad ecosystem
• SparkPost – strong delivery tooling
• Resend – modern API, popular with dev teams, especially for product emails

2) Marketing / lifecycle email

For newsletters, campaigns, automations.

• Customer.io
• Braze
• Klaviyo
• Iterable
• Mailchimp / Brevo / Campaign Monitor

3) Simple API + decent deliverability

If you want something easy to swap in.

• Postmark
• Resend
• SendGrid
• Amazon SES if you can handle setup

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If deliverability is the main issue

Before switching, check these first—often the platform isn’t the only problem:

• SPF, DKIM, DMARC correctly configured
• Sending from a custom domain and aligned From/Return-Path
• Proper bounce handling
• Low spam complaint rate
• Clean recipient list and suppression management
• Good content: avoid spammy subject lines, broken HTML, URL shorteners, image-only emails
• Domain/IP reputation issues
• Warm-up if you recently started or changed sending patterns
• Segmenting transactional vs marketing traffic

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Quick recommendations

• Want the best “just works” transactional email: Postmark
• Want cheap and scalable: Amazon SES
• Want modern dev experience: Resend
• Want all-in-one with lots of features: SendGrid
• Want strong marketing automation: Customer.io / Klaviyo / Braze

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Practical advice

If you’re switching because of deliverability, consider:

1. Move transactional and marketing to separate providers
2. Use a dedicated sending domain/subdomain
3. Monitor inbox placement, bounces, and complaints
4. Run a small parallel test before fully migrating

If you want, I can give you:

• a side-by-side comparison table of Mailgun vs Postmark vs SES vs SendGrid vs Resend, or
• a migration checklist for moving off Mailgun without breaking deliverability.