Choosing email infrastructure for AI agents? Here's how LoftBox compares to AgentMail, Mails.ai, and RobotoMail on the things that matter when an autonomous agent sends and receives real email: developer access, the Model Context Protocol, standard mail protocols, and—crucially— governance (approval, audit, and data protection).
| Capability | LoftBox | AgentMail | Mails.ai | RobotoMail |
|---|---|---|---|---|
| Send & receive mailboxes | Yes | Yes | Yes | Yes |
| Official SDKs | Yes — 8 languages: Python, TypeScript, Go, Rust, PHP, Java, Ruby, .NET, with Laravel / Spring Boot / Rails / ASP.NET integrations | Python, TypeScript, Go | Python, TypeScript | CLI only |
| Official MCP server | Yes — npx @loftbox/mcp, with approve/reject tools | Yes | Yes — npx @mailsai/mcp-server | No |
| SMTP submission + IMAP | Yes — mail.loftbox.net :587 / :993 | Yes | No | No |
| Human-in-the-loop approval | Yes — policy-driven approval gate before send | Basic (draft / allowlist) | Not documented | No |
| Audit log | Yes — every action recorded | Not documented | Not documented | Not documented |
| Inbound prompt-injection screening | Yes — every received message scored across 6 categories, risk signal on API & webhook | Not documented | Yes — 6-category scanner | No |
| Inbound sender allow / block rules | Yes — per-mailbox or org-wide, matched on spoof-resistant envelope sender | Allowlist | Reputation auto-suppress | No |
| Full-text message search | Yes — subject, body, sender/recipient, with highlights | Yes | Not documented | Basic |
| GDPR controls (export / delete-all / retention) | Yes — Art. 20 / 17 / 30 | Not documented | Not documented | Not documented |
| Web console (GUI) | Yes | API-only | Not documented | Yes |
| Self-hosted mail delivery | Yes — own MTA | — | No — managed pool | — |
| Dedicated IP + auto-warmup | Via self-hosted MTA | Not documented | Yes — $50/mo add-on, ~14-day warmup | — |
| UI languages | 20 | English | English | English |
| Free tier | Yes — 3 mailboxes, 100 emails/day, 1 custom domain | Yes — 3 inboxes, 100/day | Yes — Free $0 (Pro $20 / Scale $99) | Paid only |
Based on publicly available information as of June 2026. Competitor offerings change—check their current docs.
An AI agent sending email on your behalf is a liability without controls. LoftBox gates outbound mail behind policy-driven approval (a human approves or rejects before anything sends), records every action in an audit log, and ships GDPR controls—data export, delete-all, and retention—out of the box. The same approval gate is exposed through the MCP server, so even agent-driven sending stays under review.
An agent that reads its inbox is reading attacker-controllable text. LoftBox scores every received message for prompt-injection across six categories—instruction override, role hijack, tool injection, data exfiltration, hidden text, and encoding evasion—and exposes the risk score on the Message API and inbound webhook, so an agent can decide before acting. Sender allow/block rules matched on the spoof-resistant SMTP envelope sender stop unwanted mail before it ever reaches the agent.
LoftBox runs its own mail transfer agent—DKIM/SPF/DMARC per custom domain—rather than reselling a third-party sending API. You get direct control over deliverability and reputation.
Published SDKs (pip install loftbox, npm i @loftbox/sdk), an official
MCP server (npx @loftbox/mcp) covering the full admin plane, and standard
SMTP submission + IMAP—so existing mail clients and tools connect directly. The
product UI ships in 20 languages.
AgentMail is a mature, well-funded option with a broad SDK lineup; if you only need API-first send/ receive and don't need deep governance or a GUI, it's a solid choice. Mails.ai overlaps closely on agent positioning—MCP server, inbound prompt-injection scanning, and a Python/TypeScript SDK—and adds deliverability extras like a dedicated-IP add-on with ~14-day auto-warmup, per-agent reputation scoring, and per-event pricing; if isolated sending reputation and usage-based billing matter more than standard mail protocols, governance, or a 8-language SDK surface, it's worth a look. RobotoMail offers a simple GUI-first experience. LoftBox is the strongest fit when you need standard SMTP/IMAP access, oversight, auditability, and data-protection guarantees for agents acting on real email.
LoftBox is API-first email infrastructure for AI agents. Agents get real email identities that send and receive, with governance built in—human-in-the-loop approval, audit logging, GDPR controls, per-org quotas, inbound prompt-injection screening, and self-hosted delivery.
Yes—3 mailboxes, 100 emails per day, and 1 custom domain.
Eight: Python, TypeScript, Go, Rust, PHP, Java, Ruby, and .NET—plus Laravel, Spring Boot, Rails,
and ASP.NET integrations, an official MCP server (npx @loftbox/mcp), and standard
SMTP submission and IMAP.
LoftBox scores every received message for prompt-injection across six categories and exposes the risk score on the Message API and inbound webhook, so an agent can decide before acting. Sender allow/block rules matched on the spoof-resistant envelope sender add a second layer.
Yes. LoftBox runs its own MTA with custom domains and DKIM/SPF/DMARC, rather than reselling a third-party sending API.
It can—policy-driven approval gates require a human to approve or reject before sending, exposed through the API and the MCP server.
Yes—SMTP submission on port 587 (STARTTLS) or 465 (implicit TLS), IMAP on 993, with your API key as the password.
LoftBox — API-first email infrastructure for AI agents. Send/receive mailboxes, human-in-the-loop approval, audit logging, GDPR controls, SDKs, MCP, SMTP & IMAP.