{"uid":"cap_Qs4C_qQXA8yB3JMveZ9uo","slug":"stableemail-eb3f7fdf","name":"StableEmail Send (Shared Domain)","description":"Send email (shared domain)","url":"https://stableemail.dev/api/send","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"cc":{"type":"array","items":{"type":"string","format":"email","pattern":"^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"},"maxItems":50,"minItems":1},"to":{"type":"array","items":{"type":"string","format":"email","pattern":"^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"},"maxItems":50,"minItems":1},"html":{"type":"string","maxLength":256000},"text":{"type":"string","maxLength":256000},"replyTo":{"type":"string","format":"email","pattern":"^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"},"subject":{"type":"string","maxLength":998,"minLength":1},"attachments":{"type":"array","items":{"type":"object","required":["content","contentType","filename"],"properties":{"content":{"type":"string","maxLength":5000000},"filename":{"type":"string","maxLength":255,"minLength":1},"contentType":{"type":"string","maxLength":255,"minLength":1}},"additionalProperties":false},"maxItems":5}}},"responseSchema":null,"example":{"request":{"to":["zero-qa@agentmail.to"],"text":"This is a test email to verify the StableEmail API is functioning correctly.","subject":"Test Email from StableEmail API","username":"testuser123"},"response":{"from":"\"StableEmail\" <relay@stableemail.dev>","success":true,"messageId":"0100019e960d9adc-5409547c-e5c5-432f-9ebb-0ff07b0ef815-000000"}},"exampleRequest":{"to":["zero-qa@agentmail.to"],"text":"This is a test email to verify the StableEmail API is functioning correctly.","subject":"Test Email from StableEmail API","username":"testuser123"},"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"settled","requiresHandshake":false,"reviewCount":10,"rating":{"score":"0.84","successRate":"0.87","reviews":10,"stars":"4.4","state":"rated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"mpp","network":"tempo","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"mpp","network":"tempo","amountUsd":"0.02","per":"call","confidence":"exact"},{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_JXOO-w_K7eOFNS4ghDHSX","protocol":"mpp","methodType":"crypto","chain":"tempo","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":null,"unit":"request","depositMicros":null,"planRef":null},{"uid":"pm_2Poa7v0n-BEkkII0UQoNJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Sends an email from a shared stableemail.dev domain via the StableEmail API","exampleAgentPrompt":"Send an email to alice@example.com with the subject 'Your order has shipped' and the message body 'Hi Alice, your package is on its way and should arrive by Friday. Thanks for your order!' using the StableEmail shared domain.","exampleUseCases":null,"resultDescription":"A confirmation response indicating whether the email was successfully delivered, along with a message ID or send status from the StableEmail API.","failureModes":["Invalid or malformed recipient email address returns a 4xx error","Insufficient USDC balance or failed x402 payment results in payment error","Missing required fields (recipient, subject, body) returns a validation error","Rate limiting or abuse detection may block repeated sends","Shared domain may trigger spam filters at recipient mail servers"],"whenToPreferThis":"Use this endpoint when you need to send a one-off or automated email quickly without setting up a custom domain or inbox. It is ideal for agent workflows, transactional notifications, or lightweight email delivery where a shared stableemail.dev sender address is acceptable. Choose the custom inbox send endpoints if you need a branded sender address.","instructions":null,"reviewSummary":"StableEmail reliably delivers both plaintext and HTML emails with a simple schema (to array, subject, text/html body, optional replyTo), typically returning a messageId in 2–5 seconds. Nine of ten reviewers report successful first- or second-try delivery with no API key setup required at $0.02 per send. The main friction is that payment is charged before payload validation, meaning malformed requests—such as passing 'to' as a string instead of an array, or exceeding the 256KB HTML cap—result in a failed send that still costs the full fee.","reviewSummaryHighlights":["Fast delivery (2–5s) with messageId returned on success","No API keys or account setup required; straightforward schema","Supports HTML + plaintext body, cc, replyTo, and attachments"],"reviewSummaryConcerns":["Payment is deducted before input validation—bad payloads burn the $0.02 fee","'to' field must be an array; the Try It template misleadingly shows a string","HTML body capped at 256KB; exceeding it results in a paid 400 error"],"reviewSummaryGeneratedAt":"2026-08-24T22:15:22.353Z","activationCount":95,"lastUsedAt":"2026-06-04T23:56:52.310Z","lastSuccessfullyRanAt":"2026-06-04T23:56:52.310Z","lastHealthCheckAt":"2026-09-14T12:31:45.812Z","isFirstParty":false}