BYO sending keys lets you connect your own provider (SES, Resend, Postmark, Mailgun, SendGrid) to an email platform, so it runs campaigns while your provider sends.
BYO (bring-your-own) sending keys is a model where an email marketing platform uses your credentials with a sending provider rather than its own infrastructure. You stay on your existing sending provider; the platform sits on top as the operator.
Practically: you give the platform your Amazon SES IAM key, or your Resend API token, or your Postmark server token. The platform pushes messages through that provider, using your domain's deliverability reputation and your account's pricing.
Cost. SES at $0.10/1K is dramatically cheaper than most platforms' bundled pricing at volume. BYO lets you use SES economics while keeping a product layer on top.
Deliverability reputation. If you've been on Postmark or Resend for years and have a clean sender reputation, BYO keeps that reputation. Moving to another platform's shared infrastructure resets you to zero.
Vendor leverage. If you can swap the sending provider without swapping the platform, both vendors have to compete on price and reliability. Your costs stay rational.
Data sovereignty. Some organisations require sending through a specific provider (AWS for compliance, for example). BYO satisfies that without locking you out of modern platforms.
Not just SMTP credentials. True BYO integrates with the provider's API and webhook surface, so bounce, complaint, and delivery events flow back to the platform's contact state.
Not free. The platform still charges for its platform layer (templates, AI, MCP, campaigns, flows). You pay your sending provider directly for the sends, and the platform for what it uniquely provides.
Not a way around deliverability rules. Your sending provider still enforces their own anti-spam, authentication, and volume ramp requirements.
nitrosend offers BYO on Pro, Ultra, and Enterprise plans. Supported providers: Amazon SES, Resend, Postmark, Mailgun, SendGrid.
Most legacy ESPs (Mailchimp, Klaviyo, ActiveCampaign, Campaign Monitor) do not offer BYO. It conflicts with their per-send revenue model.
Some modern developer-focused tools (Customer.io, Stensul) offer partial BYO for specific stacks.
Upgrade to Pro or higher. In account settings, open Providers, add your SES, Resend, Postmark, Mailgun, or SendGrid credentials. Verify the sending domain if you haven't already. nitrosend routes outbound sends through the provider you chose.
Yes. You can configure a primary and a failover, or route marketing through one and transactional through another.
Positively if you've got an established reputation on your existing provider (BYO preserves it). Neutral if you're starting fresh. The platform layer doesn't change deliverability; the sending provider does.
At high volume, usually yes, because AWS SES at $0.10/1K beats most shared-infrastructure pricing. Break-even is usually around 50-100K emails/month.