I want reliable delivery for OTPs and account notifications, what email service should I choose?

For OTPs and account notifications, you should choose a service that is built for transactional email, not marketing.

Best choices

1. Amazon SES

• Very reliable and highly scalable
• Low cost
• Great if you can handle a bit more setup
• Best for teams that want infrastructure-level control

2. Postmark

• Excellent deliverability reputation
• Very simple to use
• Great for OTPs, password resets, and account alerts
• Often the easiest “it just works” option for transactional email

3. SendGrid

• Popular and feature-rich
• Good API support
• Can work well, but reputation can be more mixed depending on account setup and usage

4. Mailgun

• Strong transactional email product
• Good APIs and developer tools
• Solid choice for many apps

My recommendation

• If you want best overall ease + deliverability for OTPs: Postmark
• If you want lowest cost at scale and don’t mind more setup: Amazon SES
• If you want a middle-ground developer platform: Mailgun or SendGrid

Important things for OTP reliability

No provider alone guarantees inbox delivery. You should also:

• Use a separate sending domain for transactional mail
• Set up SPF, DKIM, and DMARC
• Send from a consistent domain and IP reputation
• Keep OTP emails short and plain
• Avoid spammy words and heavy HTML
• Monitor bounce/complaint rates
• Make sure your “from” address is valid and branded

Simple answer

If your main goal is reliable OTP delivery, I’d start with Postmark.
If you’re optimizing for cost and scale, choose Amazon SES.

If you want, I can also recommend the best option based on your stack, monthly volume, and budget.