Menu
DocsPricingAgent skillSign in
Create a mailbox

Robotomail vs Mailgun for Automated Email

Mailgun is a developer email service focused on transactional sending and email validation. While it supports inbound routing, the setup is complex and there's no concept of persistent agent mailboxes. Robotomail is built specifically for AI agents that need to send, receive, and manage email conversations.

Feature
Mailgun
Robotomail
Inbound email
Inbound routing via Routes with regex matching. Complex setup, no persistent mailbox.
Every mailbox receives email natively. Inbound delivered via HMAC-signed webhooks.
Mailbox model
No concept of individual mailboxes. Messages sent from domain-level addresses.
Real mailboxes per agent. Each has its own address and send limits.
Getting started
Requires domain verification and DNS configuration before sending any email.
Instant platform mailbox on robotomail.co. Custom domains available when ready.
Inbound setup
Configure MX records, create Routes with match expressions, handle MIME parsing yourself.
Register a webhook URL. Receive parsed JSON with headers, body, and attachments.
Threading
No built-in threading. You must track message references manually.
Automatic threading via In-Reply-To and References headers, with subject fallback.
Pricing model
Per-email pricing. Limited free trial, then paid tiers based on volume.
Per-mailbox tiers. Free: 3 mailboxes, 5,000/mo, 100 sends/day per mailbox, no time limit.
API design
General-purpose email API. Endpoints organized around messages, domains, and events.
Agent-first API. Endpoints organized around mailboxes, threads, and webhooks.

Mailgun routes versus real mailboxes

Mailgun supports inbound workflows through routes, which can be powerful for rules-driven processing. The tradeoff is that you still do not get a persistent mailbox model for each agent. Teams have to stitch together route matching, MIME parsing, and state tracking in their own application.

That can be acceptable for simple forwarding or one-way ingestion, but it becomes fragile when an agent needs a stable inbox, conversation context, and a predictable send-receive loop. Those are the places where the operational overhead of a routes-first model starts to show up.

Why Robotomail is simpler for agent workflows

Robotomail treats the mailbox as the core primitive. Agents get an address immediately, inbound mail arrives as parsed JSON, and replies stay tied to the original thread without extra glue code. That shortens the path from prototype to production for support, sales, and assistant-style agents.

It also reduces sequencing risk. Teams can start on platform mailboxes, validate the workflow, and only then move to custom domains if needed. That staged setup is usually easier than requiring domain and routing work before the first end-to-end test can happen.

Common questions

Does Mailgun support inbound email?

Yes, but through route-based workflows rather than durable agent mailboxes. You still need to own the application logic that turns those events into conversations.

When would Mailgun still make sense?

It remains a good fit for high-volume sending and validation use cases that do not require per-agent inboxes.

What is the main implementation difference with Robotomail?

Robotomail gives you a mailbox-first API, so receiving, replying, and threading are part of the product instead of extra plumbing you build around it.

Ready to give your agent a real mailbox?

Get started free