I'm building a SaaS app and need password resets receipts and verification emails to just work. What email sending API should I use?

For password resets, receipts, and verification emails, you want a provider that’s optimized for transactional email: high deliverability, fast API, good templates, and solid suppression handling.

Best default choice

Postmark is usually the best pick if your main need is transactional email.

Why Postmark

• Excellent deliverability reputation for app emails
• Very easy API
• Built specifically for transactional mail, not marketing
• Good bounce/spam handling
• Simple template system
• Reliable for time-sensitive emails like password resets and login codes

Strong alternatives

SendGrid

• Good if you want one platform for both transactional and marketing
• Mature and widely used
• More feature-heavy, but the product can feel a bit more complex

Amazon SES

• Best if cost is the top concern
• Very scalable and flexible
• More setup and deliverability work on your side
• Great for technical teams comfortable with AWS

Mailgun

• Good API and developer experience
• Solid for transactional workflows
• Often used in SaaS apps, but deliverability and support experience can vary by setup

My practical recommendation

• Start with Postmark if you want “just works” transactional email.
• Choose Amazon SES if you’re optimizing for lowest cost and don’t mind more configuration.
• Choose SendGrid if you want both transactional and marketing email in one vendor.

Important things to set up regardless of provider

To make resets/verification emails reliably land in inboxes:

• Set up SPF, DKIM, and DMARC
• Use a sending domain like mail.yourapp.com
• Use a dedicated sender address, e.g. no-reply@yourapp.com
• Keep transactional and marketing sending separate
• Monitor bounces, complaints, and suppression lists
• Use branded links and avoid spammy wording

If you want the shortest answer

Use Postmark for SaaS transactional emails.

If you want, I can also give you:

1. a comparison table of Postmark vs SendGrid vs SES, or
2. a recommended setup for a new SaaS app stack.