Email API pricing for AI agents
Pay for what flows: $0.15 per 1,000 accepted recipients or inbound emails. Rejected addresses are free. No seat fees, no mailbox fees, no minimums.
- $0.15/ 1,000
- Per accepted recipient or inbound email
- $0.25/ 1,000
- Per accepted recipient, managed SES
- $0.02/ GB · mo
- Mailbox storage
What it costs
Three numbers. That's the whole price list.
No tiers to decode and no plan to outgrow. Sendmux meters three things by usage, and every charge shows up in your balance and transactions. You start free and only pay once billable usage begins.
Standard usage
Each recipient your providers accept, plus each inbound email you receive.
Managed Amazon SES
Each recipient accepted through the built-in account.
Mailbox storage
Metered across all of your team's mailboxes.
Enterprise
Dedicated infrastructure, priority support, volume pricing, and SLAs.
Each To, CC, or BCC recipient your provider accepts counts once. Addresses rejected before acceptance are free. Inbound mail is metered per email.
Estimate
Estimate your monthly bill
Drag the sliders to your volume. The estimate updates as you go, with no sign-up and no email gate.
Estimated monthly cost
$15.20
Estimate only. Inbound mail rejected by your sender rules isn't billed.
Included
No per-seat fees. No per-mailbox fees. No surprises.
A free sending account
Every team gets a managed Amazon SES route on sign-up, capped at 50 emails a day. Raise it in one click.
Roles for people, keys for code
Add as many teammates as the work needs. Billing never counts seats, and scoped keys limit each service to its job.
Logs, metrics, and isolation
Delivery logs, usage metrics, and team-level isolation come with every account, never a higher tier you upgrade into.
How the bill is built
A simpler shape than tiered plans
Most email tools price by plan tier, then bill overage on top. A few charge by the inbox. Sendmux meters accepted recipients and inbound email.
Price jumps at each tier, then overage stacks on top.
step → step → overageThe bill scales with inbox count, not the mail itself.
+inbox → +blockThe bill rises with accepted recipients and accepted inbound emails.
usage → bill, linearSendmux
- Pricing model
- Per accepted recipient or inbound email
- Per-seat fees
- None
- Per-mailbox fees
- None
- Send and receive
- One rate, one bill
- Bring your own provider
- Any SMTP, weighted
Transactional email APIs
- Pricing model
- Tiered plans plus overage
- Per-seat fees
- Often gated to higher plans
- Per-mailbox fees
- Not applicable
- Send and receive
- Inbound often gated
- Bring your own provider
- Locked to their sending
Agent inbox providers
- Pricing model
- Per-inbox tiers
- Per-seat fees
- Bundled by tier
- Per-mailbox fees
- Inbox count sets the price
- Send and receive
- Inbox-native
- Bring your own provider
- Not supported
Based on public pricing pages, May 2026. Compared by category, not by named vendor.
Enterprise
Bigger volume, dedicated infrastructure
Past a few million emails a month, or when you need dedicated infrastructure, priority support, and a custom SLA, we'll price around your volume instead of a public rate. Same API, same usage model, no per-seat tax.
Pricing FAQ