Founding Product Engineer

Introducing Domain Connect. JMJoseph Maregn October 16, 2026 Connect a custom domain to AgentMail through Vercel or Cloudflare in a few clicks, with no DNS records to copy by hand. Built on Domain Connect and available through the API. custom-domains domain-connect Your agents deserve their own email address. Setting one up shouldn't be the hard part. Today, AgentMail, Inc. is introducing Automatic Domain Setup, powered by Domain Connect and launched in partnership with Vercel and Cloudflare. Add a custom domain to AgentMail, click Set up with Vercel or Set up with Cloudflare, approve the DNS changes with your provider, and come back to AgentMail for verification. There are no DNS records to copy by hand. The same flow is available through the API, so an agent can start the setup itself and a person only has to approve it. * What it is: AgentMail now connects custom domains through Domain Connect, an open DNS standard. Domains on Vercel and Cloudflare can be set up in a few clicks instead of by copying records. * Why AgentMail, Inc. built it: 42.1% of new customers who added a custom domain in the past month hit at least one verification failure, almost always from a small mistake made while copying records. * How it works: AgentMail generates the records and sends them to your DNS provider through a signed link. The provider shows you the changes, and nothing is applied until you approve them. * For agents: GET /v0/domains/{domain_id}/setup-link returns the signed link, so an agent can create a domain and start the setup without a developer assembling records. One of the things AgentMail, Inc. has always believed at AgentMail is that AI agents should be first-class citizens on the internet. That means having their own identities, their own inboxes, and the ability to communicate with the outside world. Increasingly, developers want those identities to live on their own domains. Until now, getting an agent set up with a custom email domain has been more complicated than it needed to be. Why is setting up a custom email domain so frustrating? Setting up a custom domain meant moving back and forth between AgentMail and your DNS provider, copying records by hand, and waiting for verification. That's five DNS records, verification checks that back off exponentially and stretch out the wait, and many points of failure. In fact, 42.1% of new customers who added a custom domain in the past month encountered at least one verification failure. Sometimes it was a missing character. Other times it was a duplicated domain suffix, or a record entered in the wrong place. These failures come from copying and pasting records manually, and every DNS provider has its own interface for entering them. A small mistake could turn what should have been a quick setup into a frustrating debugging session. AgentMail, Inc. wanted to change that. How does one-click domain setup work? AgentMail, Inc. has partnered with Vercel and Cloudflare to make connecting your custom domain to AgentMail much simpler. Instead of copying DNS records, you connect your domain directly through your DNS provider: * Add your custom domain to AgentMail. * Click Set up with Vercel or Set up with Cloudflare. * Review and approve the DNS changes with your provider. * Return to AgentMail for verification. That's the whole flow. There's no back and forth between tabs and no records to copy and paste. Can an agent set up a custom domain through the API? Yes. AgentMail, Inc. didn't want this to stop at the console, so Automatic Domain Setup is available through the API as well. Your agent can create a domain, request a configuration link, and start the setup process without a developer assembling DNS records: # 1. Create the domain curl -s -X POST "https://api.agentmail.to/v0/domains" \ -H "Authorization: Bearer $AGENTMAIL_API_KEY" \ -H "Content-Type: application/json" \ -d '{"domain": "example.com"}' # 2. Request a setup link for it, using the domain_id from step 1 curl -s "https://api.agentmail.to/v0/domains/$DOMAIN_ID/setup-link" \ -H "Authorization: Bearer $AGENTMAIL_API_KEY" { "supported": true, "provider_name": "Cloudflare", "url": "https://...", "state": "..."} Open url for the domain owner to approve, and store state first so you can check it when the provider redirects back. If the provider isn't supported, supported comes back false and the records can be added manually. The setup link reference covers every field, including the popup size and the warning returned when the domain already has another email provider's MX records. The domain owner still reviews and authorizes the changes with their DNS provider, but the rest of the workflow can be orchestrated programmatically. How does Domain Connect work under the hood? Automatic Domain Setup is powered by Domain Connect, an open standard for simplifying DNS configuration. AgentMail generates the records required for email delivery and authentication, then passes them to your DNS provider through a signed configuration link. The provider presents the proposed changes for approval before applying them. Because the link is signed, the provider knows the records came from AgentMail and weren't edited along the way. What does it not cover yet? Automatic Domain Setup works today for domains whose DNS is hosted on Vercel or Cloudflare. Domains on other providers still use the manual flow in the custom domains guide, and AgentMail, Inc. is adding more providers. It also doesn't remove the approval step. Someone with access to the DNS account has to approve the changes, which keeps a person in control of what gets written to the domain. Custom domains are available on paid plans, as listed on the pricing page. What does this mean for agents? AgentMail, Inc. is working toward a future where developers can give agents everything they need to operate independently: identities, inboxes, authentication, and the ability to communicate with people and services. That future requires making infrastructure that was designed for humans easier for agents to use. Custom domain configuration is one small but important piece of that. If you're running many agents across many domains, how to manage custom domains for thousands of agent inboxes covers which agents should share a domain and which should get their own. With Automatic Domain Setup, developers can spend less time configuring email infrastructure and more time building what their agents can do. It's available today for domains using Vercel and Cloudflare, with more providers coming soon. Try it in the AgentMail console. AgentMail is the first email provider built for AI agents. Create an inbox in one API call, send and receive email, no OAuth and no domain verification. Free tier, no credit card required. Faq. AgentMail connects custom domains through Domain Connect, so on Vercel or Cloudflare you click a setup button, approve the DNS changes with your provider, and AgentMail verifies the domain with no records copied by hand. The same flow is available through the API, so an agent can create the domain and request the setup link itself, and the domain owner only has to approve it.

SendMux vs AgentMail: Which Email API for AI Agents Wins in 2026? AI Infrastructure Lead July 8, 2026 Key takeaways. * SendMux routes through your own providers (SMTP, Gmail, Microsoft 365, Amazon SES) with weighted delivery and automatic failover - you keep your sender reputation. Pure usage pricing: $0.15 per 1,000 emails, no per-inbox fee. * AgentMail is a fully managed inbox platform (YC-backed, $6M seed). Zero setup, a real free tier (3 inboxes, 3,000 emails/mo), and plans that scale by inbox count. * Both give agents real two-way inboxes, custom domains, real-time events, and an MCP server. SendMux ships 5 SDKs; AgentMail ships 2 (Python, TypeScript). * Pick SendMux to protect existing deliverability and pay pure usage. Pick AgentMail for the fastest zero-config start and a free tier. Giving an AI agent a real email address used to mean gluing together a transactional sender, an IMAP inbox, a webhook parser, and a pile of retry logic. In 2026, two tools do all of that for you - and they take opposite approaches. SendMux sits on top of the providers you already use. AgentMail owns the whole stack and hands you a managed inbox. Popularaitools has reviewed both in depth; this is the head-to-head on the decisions that actually matter. At a glance. | Dimension | SendMux | AgentMail | | Delivery model | Bring your own providers + failover | Fully managed infrastructure | | Agent inboxes | | Native | | Native | | Real-time events | Webhooks, SSE, polling | Webhooks, WebSockets | | MCP server | | | | | | SDKs | TS, Python, Go, PHP, Ruby | Python, TypeScript | | Free tier | Free to start (usage-based) | | 3 inboxes, 3,000 emails/mo | | Pricing | $0.15 / 1,000 emails | Free, $20, $200, custom | | Backing | Independent | Y Combinator, $6M seed | Architecture: your providers vs their infrastructure. This is the fork that decides everything else. SendMux is a control plane over providers you own. You connect SMTP, Gmail, Microsoft 365, or Amazon SES, optionally spread volume across weighted delivery groups, and SendMux orchestrates routing and failover on top. Your mail sends from your accounts, so your existing sender reputation and deliverability carry over. AgentMail is the opposite bet: a fully managed platform. It provisions inboxes on its own infrastructure and handles delivery for you. There's nothing to connect - you call one endpoint and get a live, real inbox back. That's less control over the sending path, but far less to set up, and it's the reason an AgentMail agent can be live in about four lines of code. The trade is clean: SendMux for control and reputation portability, AgentMail for zero-config speed. If you've already warmed up sending domains on SES, SendMux lets you keep them. If you're starting fresh and just want an inbox that works, AgentMail removes the entire provider question. Inboxes and events: both nail the agent basics. Here the two are closer than you'd expect. Both give every agent a real, addressable inbox on a shared domain or your own verified domain. Both support full threading and attachments, and both return agent-friendly data - SendMux strips signatures and quoted history by default so your model reasons over the actual message. On real-time events they diverge slightly. SendMux offers webhooks, Server-Sent Events, and change polling - three ways to fit different runtimes. AgentMail offers webhooks and WebSockets. Both also expose an MCP server, so an MCP-aware agent like Claude can call inbox tools directly. If you live in the Model Context Protocol world, either one drops in cleanly. One practical difference: SDK coverage. SendMux ships official SDKs for TypeScript, Python, Go, PHP, and Ruby plus a CLI. AgentMail ships Python and TypeScript. If your stack is Go or Ruby, SendMux saves you from hand-rolling against the REST API. Pricing: usage-based vs plans with a free tier. The pricing models are as different as the architectures. SendMux is pure usage: $0.15 per 1,000 emails sent or received through your providers, $0.25 per 1,000 through managed Amazon SES, and $0.02 per GB of storage. No per-seat fee, no per-mailbox fee, no subscription. A million emails a month lands around $150, and because there's no per-inbox charge, you can hand out thousands of agent inboxes without the bill exploding. AgentMail uses plans with a genuinely useful free tier: Free ($0, 3 inboxes, 3,000 emails/mo), Developer ($20/mo, 10 inboxes, 10,000 emails), Startup ($200/mo, 150 inboxes, 150,000 emails, SOC 2), and custom Enterprise. The free tier is the standout - you can build and ship a real agent without paying anything. The catch is that plans scale on inbox counts, so a fleet of many small inboxes can jump tiers faster than SendMux's flat per-email math. Rough rule of thumb: AgentMail is cheaper to start and at predictable mid volumes with a handful of inboxes. SendMux wins when you have many inboxes or high, spiky volume where pure per-email pricing beats inbox-count tiers. Which should you choose? Choose SendMux if... * | You already have sending providers and want to keep your reputation * | You need multi-provider failover and weighted delivery * | You want pure usage pricing with no per-inbox fee * | You're spinning up many inboxes or have spiky volume * | Your stack is Go, Ruby, or PHP (more SDKs) Choose AgentMail if... * | You want the fastest zero-config start * | You want a free tier to build and test on * | You'd rather not manage sending providers at all * | You value YC backing and a funded roadmap * | You're on Python or TypeScript There's no wrong answer here - both are excellent, and both are genuinely built for agents rather than retrofitted from a marketing-email tool. The decision comes down to a single question: do you want to own the sending path, or hand it off? Own it with SendMux; hand it off with AgentMail. Read the full reviews Frequently asked questions. What's the core difference between SendMux and AgentMail? SendMux routes email through your own providers with failover and charges pure usage ($0.15/1,000). AgentMail is a fully managed inbox platform with a free tier and plans that scale by inbox count. Which is cheaper? AgentMail is cheaper to start (free tier) and at predictable mid volumes. SendMux wins with many inboxes or high, spiky volume thanks to flat per-email pricing and no per-inbox fee. Do both work with Claude and MCP? Yes. Both ship a Model Context Protocol server, so MCP-aware agents like Claude can call their inbox tools directly without custom glue code. Are You Building an AI Tool? Get your tool listed in front of thousands of developers, creators, and businesses searching for AI solutions For AI Builders Get your AI Tool in front of 50,000+ monthly readers. PopularAiTools.ai reaches developers, founders, and AI buyers actively searching for their next tool.