AgentMail vs Mailgun (2026): Pricing, Inbound, and AI-Agent Coverage

If you landed on "agentmail vs mailgun" you are weighing an AI-agent email platform against the long-running developer transactional service. Two different shapes of product: AgentMail gives every agent an inbox; Mailgun is a high-volume sending API with a deliverability suite sold around it. Where each one wins, what 2026 pricing actually looks like, and the operational gaps that matter.

Pricing accurate as of May 2026; check the AgentMail pricing page and the Mailgun pricing page for current rates.

At a glance

AgentMail

• Free: $0, 3,000 emails/month, 100/day cap, 3 inboxes, 3 GB storage, MCP server included, no custom domain.
• Developer: $20/mo, 10,000 emails/month, 10 inboxes, 10 custom domains, 10 GB storage.
• Startup: $200/mo, 150,000 emails/month, 150 inboxes, 150 custom domains, 150 GB storage, SOC 2 report, Slack support.
• Enterprise: custom, SSO + white-label + EU Cloud / BYO cloud.
• Inbound is a native primitive on every tier with full threading and storage.
• Webhooks signed via Svix HMAC, 5-minute tolerance, ~28h retry across 8 attempts.
• First-party MCP server with per-inbox read tools (get_message, send_message, reply_to_message).

Mailgun (owned by Sinch)

• Free: $0, 100 emails/day cap (about 3,100/month), 1 sending domain, 1 inbound route, 1-day log retention, ticket support only.
• Basic: $15/mo, 10,000 emails/month included, $1.80/1K overage, 1 domain, 5 inbound routes.
• Foundation: $35/mo, 50,000 emails/month included, $1.30/1K overage, up to 1,000 domains, email templates, 5-day log retention.
• Scale: $90/mo, 100,000 emails/month included, $1.10/1K overage, 1 dedicated IP included, SAML SSO, 5,000 email validations, send-time optimization, phone + chat support, 30-day log retention.
• Enterprise: custom, dedicated TAM.
• Dedicated IPs: $59/mo per IP additional. Required at high volumes for reputation isolation.
• Inbound is webhook-based via Mailgun Routes (and the new Forwards API as of May 12 2026); not a stored inbox.
• Webhooks signed via HMAC-SHA256 (concatenate timestamp + token, HMAC over that string using your signing key), ~8h retry across 6 attempts, no idempotency header equivalent to Svix's stable id.
• First-party MCP server v2.0.0 (released April 22 2026, open-source at github.com/mailgun/mailgun-mcp-server). Covers send, analytics, domains, webhook config, inbound routing rules, mailing lists, templates, suppression, IP pools, plus retrieving temporarily stored messages by storage key. Does not offer an inbox, thread, search, or reply toolset.

When AgentMail wins

AgentMail is built around per-agent inboxes. If your product spins up agent mailboxes that need to read replies, maintain threaded history, and act on inbound content via MCP, AgentMail's primitives are the right shape.

Specific wins:

• Per-inbox storage and threading. Mailgun has no inbox primitive at all; inbound is a webhook pipe and a temporary 3-day message store, not a searchable inbox.
• MCP coverage of inbound. AgentMail exposes get_message, send_message, and reply_to_message so an agent can read mail and reply through the standard MCP toolset. Mailgun's MCP server exposes inbound routing rule management plus stored-message retrieval by storage key, but does not expose an inbox, thread, search, or reply toolset.
• Inbound capacity on the free tier. Mailgun Free includes 1 inbound route; Basic at $15/mo unlocks 5 routes. AgentMail Free includes 3 inboxes that receive natively with full threading and storage, while a Mailgun route is webhook-only with a 3-day temporary message store.
• Multi-inbox identity. AgentMail Startup at $200/mo includes 150 inboxes that each can be a discrete agent identity with isolated storage. Mailgun has no equivalent.
• Programmatic agent onboarding so a new agent can self-provision its own inbox without a human in a console.

AgentMail loses against Mailgun on volume economics, dedicated-IP maturity, SDK breadth (9 official languages at Mailgun vs 3 at AgentMail), deliverability tooling depth via Mailgun Optimize, and send-time optimization at Scale tier.

When Mailgun wins

Mailgun is the right default for outbound-heavy transactional volume that needs a deliverability suite around it. Decade-plus shared IP pool, Optimize add-ons for inbox placement testing, and the option to scale into dedicated IPs without changing platforms.

Specific wins:

• Per-email economics at volume. Scale at $90/mo includes 100,000 emails plus a dedicated IP. AgentMail Startup is $200/mo for 150,000 emails without a dedicated IP. For pure transactional, Scale is meaningfully cheaper.
• 9 first-party SDKs (Python, Node.js, Ruby, PHP, Java, C#, Go, Perl, Luvit) plus raw SMTP relay. AgentMail covers 3 first-party SDKs.
• Mailgun Optimize add-on for inbox placement testing, blocklist monitoring, spam-trap alerts, Google Postmaster Tools + Microsoft SNDS integration. Priced separately starting at $49/mo Pilot or $99/mo Starter.
• Dedicated IPs available from Scale at $90/mo with one included. AgentMail does not offer dedicated IPs.
• Automated Sender Security: 2048-bit DKIM keys rotated every 120 days via 2 CNAMEs (pdk1, pdk2). Less manual DNS lifecycle.
• SPF DMARC alignment built into the Return-Path automatically. No separate custom MAIL FROM step needed (unlike Amazon SES).
• Send-time optimization at Scale.
• 15+ years of shared-IP reputation at the warm pool.

Mailgun loses against AgentMail on inbox primitives (none), MCP inbound coverage (stored-message retrieval by key, but no inbox, thread, search, or reply toolset), and per-agent identity (none). DMARC handling has improved: Mailgun now partners with Red Sift to generate DMARC DNS records during domain setup and supports DMARC reporting auto-generation, so this is no longer a meaningful gap.

Pricing

At ~100 emails/month (prototype)

• AgentMail Free: $0, includes 3 inboxes and inbound. Caps at 100/day.
• Mailgun Free: $0, 1 domain, 100/day cap, 1 inbound route (webhook pipe), 1-day log retention.

At 10,000 emails/month

• AgentMail Developer: $20/mo, includes 10 custom domains and 10 inboxes plus inbound and MCP.
• Mailgun Basic: $15/mo, 1 domain, 5 inbound routes, webhooks included. Cheaper for outbound with simple inbound forwarding.

At 50,000 emails/month

• AgentMail: requires Startup at $200/mo (Developer caps at 10K).
• Mailgun Foundation: $35/mo, supports up to 1,000 domains and includes email templates plus 5-day log retention.

At 100,000 emails/month

• AgentMail Startup: $200/mo, 150 inboxes, 150 domains, 150 GB storage.
• Mailgun Scale: $90/mo, dedicated IP included, 5,000 email validations, send-time optimization, SAML SSO, 30-day log retention.

At 500,000+ emails/month

• AgentMail: Enterprise (custom pricing).
• Mailgun Scale: $90/mo base + 400K overage at the $0.75/1K rate that applies above 250K = $390/mo total. Enterprise tier is custom for higher volumes.

Cost takeaway: if you need agent inbox primitives, AgentMail. If you need outbound-heavy transactional with dedicated IP and a deliverability suite, Mailgun is meaningfully cheaper above 50,000 emails/month and dramatically cheaper at 100,000+.

Developer experience

AgentMail

• API-key auth. Agent self-onboarding endpoint shipped with the $6M raise in March 2026.
• 3 first-party SDKs (Python, TypeScript, Go) plus a CLI.
• Fern-generated docs at docs.agentmail.to.
• Svix-backed webhooks expose a retry and replay UI.

Mailgun

• API-key auth. REST over HTTPS. Also supports raw SMTP relay.
• 9 first-party SDKs (Python, Node.js, Ruby, PHP, Java, C#, Go, Perl, Luvit).
• Account-level webhooks since February 17 2026: a single config fires across all domains and subaccounts.
• Forwards API (released May 12 2026) replaces Routes for simpler wildcard-forwarding workflows at scale.
• MCP server v2.0.0 (open-source, April 22 2026) compatible with Claude Desktop, Cursor, VS Code, LangChain, OpenAI Agents SDK, Vercel AI SDK.
• Dashboard depth: subaccount usage reports with CSV export (May 4 2026), bounce-rate and performance alerts deliverable via email, webhook, or Slack (November 4 2025).

Webhook reliability

Both products sign webhooks; the schemes differ.

AgentMail uses Svix:

• HMAC signature with svix-id, svix-timestamp, svix-signature headers.
• 5-minute timestamp tolerance against replay.
• Retry schedule: immediately, 5s, 5min, 30min, 2h, 5h, 10h, 10h. Total ~28h across 8 attempts.
• Stable svix-id across retries so consumers can deduplicate.
• Endpoint auto-disabled after 5 consecutive days of failure.

Mailgun:

• HMAC-SHA256 signature. The signing string is the concatenation of timestamp and token (a per-event random nonce); the HMAC is computed over that string using your account signing key.
• Replay prevention requires you to cache the token and reject duplicates; not enforced by Mailgun.
• Retry schedule: 5 min, 10 min, 15 min, 1 hr, 2 hr, 4 hr. Total ~8h across 6 attempts.
• No idempotency header equivalent to Svix's stable id.
• May 2026: PII Redaction opt-in redacts recipient addresses from webhook payloads before transmission. April 2026: MX host IP included in delivered event payloads. May 8 2026: inbound webhook payloads now include SPF, DKIM, and DMARC authentication results.

If your handler needs longer retry windows or guaranteed dedup, AgentMail's Svix integration is the friendlier option. If you want PII-redaction on outbound webhooks and richer inbound authentication metadata, Mailgun's recent additions are real upgrades.

The third option you should consider: Bavimail

The honest framing: Bavimail is not the cheapest at volume past Pro tier, and it does not match Mailgun's 15-year shared-IP reputation or Optimize tooling depth. If you ship hundreds of thousands of transactional emails per month and your only requirement is per-email economics with a dedicated IP, Mailgun Scale is the right call.

If you want both halves of email in one platform with agent-inbox primitives, MCP coverage of inbound, and signed webhooks with stable dedup, Bavimail consolidates the stack at a friendlier entry price:

• $4/mo Pro plan with 10,000 emails included and inbound on every paid tier. Mailgun Basic is $15/mo and Foundation is $35/mo for the same kind of inbound coverage.
• 5,000 emails/month permanent free tier with a 200/day cap. Mailgun's free tier caps at 100 emails/day (about 3,100/month).
• 12-tool first-party MCP server. Mailgun MCP v2.0.0 is broader on admin operations and can retrieve stored messages by storage key, but does not offer an inbox, thread, search, or reply workflow. AgentMail MCP covers reply-by-message but stops at 3-4 tools.
• HMAC-SHA256 signed webhooks with 5-minute timestamp tolerance and stable dedup id.
• __untrusted_third_party_content wrapper around inbound message bodies so an LLM agent treats attacker-controlled email content as data, not as instructions. Neither AgentMail nor Mailgun publishes a platform-level prompt-injection defense.
• Programmatic SPF, DKIM, DMARC, and MAIL FROM verification on every paid plan, returned as JSON ready to paste. Mailgun also returns SPF + DKIM via API and rotates DKIM keys every 120 days, and now partners with Red Sift to generate DMARC DNS records during domain setup; differentiation here is no longer about DMARC presence but about the single-API-call ergonomics across all four records.
• Per-agent inbox aliases on a verified domain, priced on volume rather than per-IP or per-domain.

Where Bavimail does not claim parity:

• Per-email economics above 50,000/month. Mailgun Foundation at $35/mo and Scale at $90/mo dominate for outbound-heavy transactional volume.
• Dedicated-IP maturity. Mailgun's $59/mo dedicated IPs sit on top of 15 years of shared-pool warm-up tooling and inbox-placement instrumentation via Optimize.
• SDK breadth. Mailgun covers 9 official languages plus SMTP relay. Bavimail first-party SDKs are Python and TypeScript.
• Mailgun Optimize-style separately-priced deliverability suite. Inbox-placement testing, blocklist monitoring, spam-trap alerts are not standalone products at Bavimail today.

If you came here comparing AgentMail to Mailgun because you need agent inboxes AND transactional send AND signed inbound webhooks behind one API key, the Bavimail email API for AI agents post covers the full surface. The Bavimail vs AgentMail breakdown and the Bavimail vs Mailgun breakdown give the head-to-head with pricing tables. The Bavimail pricing page shows the full tier structure. For the broader landscape of 6 AgentMail alternatives compared in one place, see AgentMail alternatives in 2026. If you also send cold outbound for sales, Bavlio is the AI-driven outreach product built on top of the same email API.

AgentMail for agent-inbox workflows, Mailgun for outbound transactional at volume with a deliverability suite, and Bavimail if both jobs need to live behind one API key with custom-domain provisioning and signed inbound webhooks included.