Reply API Labs

Power up your product with business email sending capabilities to help your users scale personal communications with just a few lines of code.

  • Email API
  • AI Assistant API
  • Email Warm-up API

Email Sending API

Enable your users to send personal or business emails at scale with Reply’s Email Sending API.

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Power up your product with email sequences

With Reply’s Email Sending API, users can connect personal or business email accounts to send email sequences, get replies, and track performance directly within your product.

Benefit from white-label solution

Reply’s Email Sending API is a white-label, ready-made email sequence engine that you can implement seamlessly into your app while keeping its UI consistent.

Scale up with compatible APIs

Email Sending API is fully compatible with other Reply APIs products:

  • AI Assistant API that detects buyer intent in emails and evaluates the probability of getting a response based on your email content;

Secure integration with a trusted provider

Reply’s API solutions are Privacy Shield certified and GDPR compliant. The user data is encrypted and isolated with multi-level permission checks, providing a full control over what data you sync.

A unified RESTful API

Use a single API that works with major providers to bring email capabilities to your app.

Multiple email providers

Connect to Gmail, Microsoft Exchange,, IMAP with just a few lines of code.

Two-way data sync

Keep the user’s account data up to date with real-time, two-way synchronization.

Highest email deliverability

Reply’s email sending engine is optimized for the best results, ensuring your emails reach the inbox.

Full control over account

Get access to both sent and received emails for included contacts via API.

Access to email content

Get email body text, sender and recipient information, subject lines, dates, pictures, etc.

Performance tracking

Keep track of bounces, auto-replies, opt-outs, out-of-office messages, and link clicks via API or file.


Use webhooks to build event-based workflows on top of Reply’s Email Sending API.

Single-Click Connect

Easily connect Gmail or Office 365 accounts to Reply in just a click.

Dedicated CS and Support

Reply’s CS and Support teams will be with you every step of the way, with 5 min response time in live chat.

Google OAuth verified

Reply is Google OAuth verified solution. Need help with Google security verification? We can help.

Branded URLs

Create branded URLs for you and your customers to use for link tracking, open and opt-out URLs.

Integrate emails in your stack now

Use Reply’s API to enable email sequencing within your apps.
Includes 24/7 help from a friendly and knowledgeable CS team.

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Frequently Asked Questions

  • How do I get started with Reply’s Email Sending API?

  • What kinds of companies use Reply Email Sending API?

  • How is the Email Sending API secured?

  • How do my users activate email sync?