AI agent email on your own domain

Picture one email, three ways. An agent reminds a customer that invoice 1042 is overdue. The text is identical every time. Only the address on top changes.

In the first version it comes from invoices-bot@agentmail.to. In the second, from invoices@northwind.com. In the third, from invoices@agents.northwind.com. The customer reads the From line before anything else, and each one says something different about who is asking for money.

A shared vendor domain is the fastest start. There are no DNS records to write, so an inbox exists a second after you ask for one. AgentMail's free plan works this way, and so does Faivelo's free agent address on fvlmail.com.

For an agent that only receives, this is often all you need. Signing up for a service and reading the verification code does not care what the domain is. We wrote that case up separately.

The trouble starts when the agent writes to people. A stranger seeing a vendor domain on a payment reminder has no reason to believe it came from Northwind. You also share the domain's reputation with every other customer of that vendor, for better or worse, and you cannot take the address with you if you leave.

invoices@northwind.com is the address customers already trust. Replies land where your team can see them, and the brand on the From line matches the brand on the invoice.

The cost is that the agent now spends the same reputation as your staff. Mailbox providers judge a domain by everything sent from it. If an agent loops and fires two hundred reminders in an hour, the bounces and complaints are recorded against northwind.com, and the CEO's next email pays for it.

For one careful agent with a human reading along, the root domain is a fair choice. For a fleet, or anything that writes to people who never wrote first, it is a lot of risk on one name.

When Google announced its Gemini coworker agents on 8 October 2026, it said each one gets a dedicated identity, "including their own @agents.company.com emails." The company that runs Gmail put its agents on a subdomain, not on the main domain and not on a google.com address.

The reasons hold for anyone. Customers still see your brand, so the trust stays. The subdomain builds a sending history of its own, so a runaway agent's bounces and complaints land on agents.northwind.com, not on the address your staff send from. And the subdomain gets its own DMARC policy, which lets you run it strictly from day one without touching the rules your staff mail lives under.

A subdomain needs the same records a main domain does, written under the subdomain's name in the parent zone. That means an MX record so mail arrives, an SPF record and DKIM keys so receivers can check the sender, and a DMARC record that tells them what to do when a check fails. You do not need to buy anything new; agents.northwind.com lives inside the northwind.com zone you already own.

Faivelo treats a subdomain like any other mail domain. It finds the parent zone, then writes the records there itself on Cloudflare, Vercel, GoDaddy, Namecheap, Route 53, Porkbun, DigitalOcean and other hosts it connects to. On any other host it shows you the records to paste.

The API side is the same as on any domain, and the walkthrough for creating mailboxes from code covers it call by call. If you have not decided between vendors yet, our agent inbox comparison lines them up on price and domain support. For price, AgentMail's free plan has no custom domains and its Developer plan is $20 a month for 10.

Use the shared address when the agent mostly listens: sign-ups, codes, receipts. Use the main domain for a single agent a person supervises closely. For everything else, a subdomain gives you the brand without betting the brand on it.

Google's choice is part of a wider shift, and we cover why agents are getting addresses at all elsewhere. The four ways to give an agent an address also go through the tools in more detail.