Postmark
Mailgun
Twilio
Resend
Mailjet
Brevo
Amazon SES
MailChimp
Sendmux.ai
Sequenzy
MailChimp
Robotomail
Klaviyo
Customer.io
Mails.ai
Resend
Sendmux is the email inbox API for AI agents. Give an agent its own mailbox, then let it receive email, read threads, inspect attachments, send replies, and react to new messages as they arrive. Each mailbox can return cleaned message content for agents, raw email when needed, signed webhooks, and Server-Sent Events for live inbox updates.
Hereโs where it helps: teams can use Sendmux for both inbound agent mailboxes and outbound email sending. Connect Gmail OAuth, Outlook OAuth, SMTP providers, or managed Amazon SES, then route mail through delivery groups with weighted routing, sender-domain routing, provider health checks, automatic failover, and quotas from per second to per day. That gives builders more control than a single-provider sending setup.
For inbound workflows, Sendmux supports custom domains with SPF, DKIM, and DMARC, mailbox-scoped API keys, sender filters, folders, labels, attachments, raw .eml downloads, IMAP retrieval, and SMTP submission. Agents can watch inbox activity through SSE, receive webhook events, or query messages and threads through the Mailbox API.
Developers can work with the Sending API, Mailbox API, Management API, OpenAPI docs, SDKs for TypeScript, Python, Go, PHP, and Ruby, the sendmux CLI, or MCP tools. Teams also get tenant isolation, provider setup, domains, logs, metrics, billing, usage tracking, and delivery history in one place.
Sendmux fits AI agent products, automation agencies, support agents, scheduling agents, ops workflows, platform builders, and controlled BYO-provider cold email setups that want to send from AI tools. Pricing is usage-based, with no per-seat fees, no per-mailbox fees, and standard email priced at $0.15 per 1,000 messages.
Postmark Sendmux.aiSendmux.ai's answer:
Publicly, Sendmux is built around REST and OpenAPI APIs, SMTP, IMAP, signed webhooks, Server-Sent Events, Model Context Protocol, SDKs for TypeScript, Python, Go, PHP, and Ruby, the sendmux CLI, and installable Sendmux Skills for agent workflows.
Sendmux.ai's answer:
Sendmux combines an email inbox API for AI agents with multi-provider outbound sending. Agents get dedicated mailboxes, mailbox-scoped API keys, cleaned message content, threads, attachments, signed webhooks, SSE live inbox events, and sending through Gmail OAuth, Outlook OAuth, SMTP, or managed Amazon SES with quotas, weighted routing, and failover.
Sendmux.ai's answer:
Choose Sendmux if you need both inbound agent mailboxes and outbound provider control. Sending-only APIs do not give agents a real inbox, and mailbox-first tools usually do not offer bring-your-own-provider routing, per-provider quotas, and failover. Sendmux gives teams one control plane for inboxes, sending, events, providers, logs, domains, billing, MCP, SDKs, Skills, and CLI access.
Sendmux.ai's answer:
Sendmux is built for AI agent product teams, automation agencies, and platform builders that need agents to send, receive, route, and react to email in production. It also fits teams using their own Gmail, Outlook, or SMTP providers for controlled outbound and cold email workflows from AI tools.
Sendmux.ai's answer:
Sendmux came from a simple problem: production AI agents need real email, not a hacked shared inbox. Teams were stitching together sending providers, mailboxes, parsers, webhook services, routing logic, and billing. Sendmux puts agent email identity, inbound mail, outbound sending, live events, and provider control into one API-first platform.
Sendmux.ai's answer:
Target Markets, CFC, Aurora Capital
Based on our record, Postmark seems to be more popular. It has been mentiond 56 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
We want to shout out Postmark for sponsoring this challenge. Postmark's developer-focused API and reliable inbound email parsing made these innovative projects possible, allowing the community to focus on creativity rather than email handling complexity. - Source: dev.to / about 1 year ago
PurifyPDF is a privacy-first PDF sanitization workflow built using n8n, Postmark, PDF.co, and Airtable. - Source: dev.to / about 1 year ago
Invisible Threads is built with Elixir, Phoenix, and most importantly, Postmark. Data lives on disk instead of a traditional database to keep the demo light. Authentication uses Postmark API tokens, mapping each application user directly to a Postmark server. The whole thing is deployed to Fly.io. A minimal setup let me focus on Postmark's offerings. - Source: dev.to / about 1 year ago
Of course, Postmark for email parsing and sending the briefings. - Source: dev.to / about 1 year ago
We are thrilled to partner with Postmark to bring the community a brand new DEV challenge. - Source: dev.to / about 1 year ago
Mailgun - A set of powerful APIs that enable you to send, receive and track email from your app effortlessly whether you use Python, Ruby, PHP, C#, Node.js or Java.
Sequenzy - AI Email Marketing Tool for SaaS & Agents. Send onboarding sequences, trial emails, and transactional messages from one platform.
Twilio - Brings voice and messaging to your web and mobile applications.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Resend - Email for developers
Robotomail - Email for AI agents. Create mailboxes, send and receive email via REST API. No SMTP, no OAuth. 30-day money-back guarantee.