Email APIs · side by side
Klaviyo vs Mails.ai
Compare Klaviyo, Mails.ai by sending volume, delivery webhooks, inbound email, domain limits and retention.
Email APIs pricing calculator
These providers bill in different units. Each estimate uses its own workload; there is no same-volume price winner.
Klaviyo
Mails.ai
Klaviyo
Custom / not listed
Custom / unlisted usage pricing · 10K profiles
Mails.ai
$0 / mo
Free · 0 sends
Listed USD plan fees and tracked usage only. Unlisted compute, transfer, extras, taxes and contract terms are excluded. Custom or unsupported plan usage is not estimated.
Email APIs overview & pricing
| Email APIs | Klaviyo | Mails.ai |
|---|---|---|
| Provider | Klaviyo | Mails.ai |
| Billing unit | profiles | sends |
| Plan at selected usage | Custom / unlisted usage pricing | Free |
| Monthly estimate | Custom / not listed | $0/mo |
| Workload | 10K profiles | 0 sends |
| Free access | Limited free plan | 3,000 events/month, 1 agent, sending via workspace subdomain, MCP server access, and SDKs with no credit card required |
| Published plans | Free | Free, Pro, Scale |
| Prices checked | 2026-10-08 | 2026-10-08 |
- Klaviyo
- Klaviyo
- Mails.ai
- Mails.ai
- Klaviyo
- profiles
- Mails.ai
- sends
- Klaviyo
- Custom / unlisted usage pricing
- Mails.ai
- Free
- Klaviyo
- Custom / not listed
- Mails.ai
- $0/mo
- Klaviyo
- 10K profiles
- Mails.ai
- 0 sends
- Klaviyo
- Limited free plan
- Mails.ai
- 3,000 events/month, 1 agent, sending via workspace subdomain, MCP server access, and SDKs with no credit card required
- Klaviyo
- Free
- Mails.ai
- Free, Pro, Scale
- Klaviyo
- 2026-10-08
- Mails.ai
- 2026-10-08
Email APIs monthly cost
Different workloads, separate estimates
Separate transactional delivery from campaigns, outreach and agent inboxes. Compare monthly sends and daily caps; contacts, seats and inboxes are not sending allowances. Budget separately for dedicated IPs, validation and attachments.
Which email providers fit your needs?
Klaviyo features & plan notes
- E-commerce data
- Omnichannel
- Shopify ecosystem
Mails.ai features & plan notes
- Inbound email parsing delivered as structured JSON with automatic prompt-injection detection
- Automatic email thread reconstruction and conversation handling via REST, SSE, or webhooks
- Native Model Context Protocol (MCP) server support alongside TypeScript and Python SDKs
- Per-agent reputation monitoring and send limits with cold outreach enforcement
- 3,000 events / month
- 1 agent
- TypeScript + Python SDKs, REST
- MCP server
- Magic-link signup, no card
How to compare email providers
Separate transactional delivery from campaigns, outreach and agent inboxes. Compare monthly sends and daily caps; contacts, seats and inboxes are not sending allowances. Budget separately for dedicated IPs, validation and attachments.
Browse Email APIs pricing