Inkbox
Inkbox gives AI agents a persistent identity with email, phone, iMessage, tunnel URL, and A2A channels.
If your agents need to receive mail and calls rather than just fire outbound alerts, Inkbox removes the ugliest part of the build: gluing telephony, email, iMessage, and A2A together by hand. $30/mo Developer is the honest production entry point, and the free tier's 2,000 shared iMessages and 3-recipient cap will bite a real support queue fast. Stitching Twilio and SendGrid yourself costs more engineering time, not less money.
Verified 3d ago · liveness 81/100 · cite: rightaichoice.com/tools/inkbox
- Developers shipping agents that must receive email, calls, or iMessage rather than only send alerts
- Teams running production agent fleets that need persistent identities and per-agent credential vaults
- Startups that want a dedicated iMessage or VoIP number so the agent can start conversations
- MCP-based setups that discover agents and manage A2A task handoffs programmatically
- Anyone wanting a plain email or phone service with no agent integration
- Teams whose agents only push outbound notifications and never need replies
- Projects requiring fully self-hosted or on-premise agent identity management
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Skip Inkbox if your agents only broadcast outbound notifications and never need replies, or if you must run a fully self-hosted identity stack.
Past your included allowance, additional SMS/MMS and call minutes cost $0.03 each for U.S./Canada numbers, dropping to $0.02 per message only if you run your own 10DLC campaign.
Free favors solo developers exploring agent reachability. $30/mo Developer fits a small production team that needs one dedicated VoIP number and custom domains. $200/mo Startup fits a fleet of roughly 100 agents with a dedicated iMessage line. Stitching Twilio plus SendGrid plus a messaging API costs less per message at scale but leaves you building identity, permissions, and memory yourself; Enterprise quotes custom volume allowances above these tiers.
In short
Inkbox — Inkbox gives AI agents a persistent identity with email, phone, iMessage, tunnel URL, and A2A channels. Best for Developers shipping agents that must receive email, calls, or iMessage rather than only send alerts, Teams running production agent fleets that need persistent identities and per-agent credential vaults, Startups that want a dedicated iMessage or VoIP number so the agent can start conversations. Free to start; paid plans from $30/mo.
What's new in Inkbox
Checked 3 days agoAcross the latest 5 updates: 2 feature updates and 3 changelog entries.
Inactive shared iMessage connections now expire after 14 days
A standard shared-service connection expires once at least 14 days old with no messages for 14 days. History stays readable and recipients can reconnect via the router. Dedicated lines and org-owned shared pools do not expire.
Phone numbers in first iMessage now require a reply
Before the recipient's first reply, one-to-one iMessage text containing phone numbers returns 422 imessage_reply_required_for_phone_numbers on every line type, including dedicated lines.
iMessage from Apple ID email addresses, receive-only
Dedicated lines accept one-to-one iMessages from non-phone senders such as Apple ID emails, delivered via imessage.received webhooks. Sends, tapbacks, typing indicators and read receipts return 422 recipient_not_e164.
Agent progress as native Slack task cards via task streams
Start, append to, and stop task streams in an existing Slack thread. Each call needs an idempotency key; SDKs and CLI never auto-retry stream writes. Native streaming depends on workspace capabilities. SDK 0.7.16.
Slack display context, custom emoji search, and file previews in one request
Message listing gains include=conversation,sender,reactions,files and roots_only, returning a deduplicated included map. Connections now expose a generation value to invalidate cached display data. SDK 0.7.15.
What people actually say about Inkbox — is it worth it?
We scanned public community sources for Inkbox on Jul 3, 2026 and could not establish that the discussion we found is about this tool rather than something else sharing its name. Our own analysis of that scan says the posts were off-subject. Rather than publish a sentiment score built on the wrong subject, we publish nothing here and re-run the scan.
Viability Score
How well maintained and how widely used is Inkbox? Built from what the vendor actually publishes (docs, changelog, tutorials, integrations, pricing), whether the site is live, and how much real users discuss it. How we calculate this
Last calculated: October 2026
How we score →Key Features
- Provision a persistent agent identity with a globally unique handle via CLI, SDK, MCP, or plugin
- Real email inbox with IMAP/SMTP mail-client access per identity
- Public tunnel URL routing inbound HTTP, WebSocket, and raw TCP without a public IP
- Real phone numbers with HD voice calls and SMS/MMS
- Shared iMessage on every plan; dedicated iMessage numbers with RCS on Startup
- Agent2Agent (A2A) brokered messaging so agents contact each other directly
- Cross-channel memory that carries context across email, SMS, and calls
- Zero-knowledge credential vault storing API keys and TOTP secrets per identity
- Directional contact rules with separate inbound and outbound permissions
- Companion mode adds an agent to existing group email, MMS, or iMessage threads
- Unified webhook subscription for email, SMS/MMS, iMessage, calls, and A2A
- Voice AI on_voicemail and voicemail_message leave a message after the beep
- DTMF keypad digits over media WebSocket to navigate phone menus (up to 20 bursts per call)
- Call forwarding to a phone or SIP address
- Slack workspace connection (beta) to read, reply, share files, search retained messages, and receive events
About Inkbox
Inkbox is an identity layer for AI agents that need to be reachable, not just chatty. Each identity bundles a globally unique handle, a mailbox on inkboxmail.com or a domain you've verified, a stable tunnel URL that routes inbound HTTP, WebSocket, and raw TCP to your runtime without opening a firewall, and optional real phone numbers with HD voice, SMS, and MMS. Shared iMessage works on every plan; dedicated iMessage and dedicated VoIP numbers arrive on paid tiers. Identity creation is agent-native. An agent can provision its own via CLI, SDK, MCP, or a plugin — `inkbox identity create sales-agent --imessage-enabled` returns a live mailbox and tunnel in seconds — and the same handle then receives email, texts, calls, and A2A traffic. Cross-channel memory keeps one person's history intact whether they email, text, or call, so an agent that wraps a call can follow up by email with the full thread. Shared org contacts carry per-agent visibility and sending permissions, and a zero-knowledge vault stores API keys and TOTP secrets per identity. Recent releases broaden where agents can operate: companion mode pulls an agent into existing group email, MMS, or dedicated-line iMessage threads at an allowed sender's request; a unified webhook subscription covers email, SMS/MMS, iMessage, call lifecycle, and A2A; SDK 0.7.10 adds idempotent send retries with a lookup to recover the original message ID; SDK 0.7.11 connects an identity into Slack workspaces (beta); and 0.7.12 adds verified domains for agent affiliation. Voice tooling now includes an on_voicemail option so outbound calls leave a message after the beep. Pricing runs Free ($0, 3 identities), Developer ($30/mo, 10 identities, one dedicated VoIP number), Startup ($200/mo, 100 identities, 9 VoIP plus one dedicated iMessage number), and Enterprise (custom). Against stitching Twilio, SendGrid, and a chat API, Inkbox gives you one identity abstraction plus memory and a vault — but per-message overages of $0.03 still
Behind the Verdict
Inkbox answers a question most agent stacks ignore until it hurts: what address does this thing live at? Give an agent a mailbox, a phone number, and a tunnel URL and suddenly it can be a teammate rather than a cron job with opinions. That's the whole product, and for support assistants, sales follow-up agents, and automated phone operators it's the right shape. Pick it when your agent must be contacted inbound and the contact history has to survive a channel switch. The cross-channel memory is the feature doing the quiet work here — a caller who then emails doesn't start over, because the identity remembers the person, not the thread. We'd also pick it for agent fleets: 100 identities on Startup with per-identity vaults beats 100 sets of credentials taped to 100 prompts. Pass if your agents only push notifications, or if you need fully self-hosted identity management — Inkbox is a hosted layer and the vendor doesn't offer an on-prem story. Teams with heavy SMS or voice volume should model the overage math before committing, because $0.03/message and $0.03/minute compound, and SMS allowances don't roll over between cycles. The closest alternative is assembling Twilio, SendGrid, and a chat API yourself. You'll get more granular carrier control and no vendor in the middle, and you'll spend weeks on identity mapping, webhook fan-in, and iMessage plumbing that Inkbox ships on day one. Twilio is the better answer if you already have telephony operations staff; Inkbox is better if you'd rather ship the agent. One real caveat on the shared iMessage router: recipients have to text first, and the recipient cap on the free tier is three simultaneous connections. That model is deliberate — it prevents cold outreach — but if your use case is the agent starting the
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Real-world workflow fit
Concrete scenarios for the personas Inkbox actually fits — and what changes day-one when you adopt it.
Runs `inkbox identity create sales-agent --imessage-enabled` from the CLI, gets sales-agent@inkboxmail.com and a sales-agent.inkboxwire.com tunnel in seconds, then wires the shared webhook subscription into an existing Python service.
Outcome: The agent receives email and iMessage replies on day one without standing up any messaging infrastructure.
Provisions an identity on the $30/mo Developer plan, attaches the dedicated VoIP number, sets directional contact rules so only known addresses get through, and stores the helpdesk API key in the vault.
Outcome: One agent handles email, SMS, and inbound calls with a single permission model and cross-channel memory of each customer.
Creates 100 identities on Startup, connects Slack (beta) for retained message search, and uses the MCP endpoint with multiple identities selected so each assistant works as an approved identity.
Outcome: Customer-facing, internal-ops, and engineering agents each keep separate handles and inboxes while sharing contacts and vault access.
Use Cases
- Customer support agent that handles email, phone, and SMS with conversation history stitched across every channel.
- Outbound sales agent that texts appointment reminders and follows up over email using the same identity.
- Automated phone operator that answers calls, navigates IVR menus with DTMF, and texts or emails mid-call.
- Developer tool agent that receives webhook callbacks on its public tunnel URL and responds by email.
- Agent that holds third-party API keys or TOTP secrets in the zero-knowledge vault and authenticates with them.
- Team of agents (engineering, GTM, ops) each with a mailbox, phone number, and iMessage presence.
- Agent joined to a Slack workspace to read retained history, search messages, and reply in channels.
- Agent that leaves a voicemail after the beep when an outbound call goes unanswered.
Limitations
- Free caps shared iMessage at 2,000 messages per month and 3 unique recipients at a time, recipients must initiate conversations and can connect to at most 3 agents at a time.
- Phone numbers are excluded on Free; dedicated VoIP numbers appear on Developer ($30/mo) and Startup ($200/mo), and a dedicated iMessage/RCS line only on Startup.
- Stored mail is capped per mailbox (1 GiB Free, 2 GiB Developer, 3 GiB Startup), and SMS/MMS and call-minute allowances (300 SMS/MMS, 30 call minutes per phone number per month, U.S./Canada) incur overage charges beyond plan limits.
- International VoIP numbers, dedicated iMessage infrastructure, and custom volume allowances require Enterprise.
as of 2026-10-08
Verification history
We have re-verified Inkbox 10 times since . Each pass re-reads the vendor's own pages and re-checks every listed field against that evidence; passes where nothing had changed are marked as such.
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
- — re-verified summary, description, our verdict, our analysis, pricing model, pricing tiers, features, integrations, who it suits, who should skip it
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12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Plans compared
For each published Inkbox tier: who it actually fits, and what it adds vs. the previous tier. Cross-reference the cost calculator above for projected annual outlay.
Free
$0/mo
Ideal for
A solo developer testing whether an agent can receive real email and iMessage before committing budget.
What this tier adds
Starting tier: 3 identities, each with an inbox, public tunnel URL, shared iMessage with calls, and an A2A channel; no phone number.
Developer
$30/mo
Ideal for
A small team running agents in production that needs a real phone number and its own sending domain.
What this tier adds
Adds 10 identities, 1 dedicated VoIP number with 300 SMS/MMS and 30 call minutes per month, 10 custom email domains, and footer watermark removal.
Startup
$200/mo
Ideal for
A startup operating a fleet of roughly 100 agents, including one that must start iMessage conversations without being texted first.
What this tier adds
Raises to 100 identities, 9 dedicated VoIP numbers, 1 dedicated iMessage number whose recipients need not initiate, and 100 custom domains.
Enterprise
Custom
Ideal for
Organizations with international reach, custom volume, or compliance needs that outgrow the published allowances.
What this tier adds
Adds volume pricing, custom allowances and higher API rate limits, international VoIP numbers, dedicated iMessage infrastructure, and white-glove onboarding.
Where the pricing makes sense
The company stage and team size where Inkbox's pricing actually pencils out — and where peers do it cheaper.
Free favors solo developers exploring agent reachability. $30/mo Developer fits a small production team that needs one dedicated VoIP number and custom domains. $200/mo Startup fits a fleet of roughly 100 agents with a dedicated iMessage line. Stitching Twilio plus SendGrid plus a messaging API costs less per message at scale but leaves you building identity, permissions, and memory yourself; Enterprise quotes custom volume allowances above these tiers.
Setup time & first value
How long it actually takes to get something useful out of Inkbox — broken out by persona, not the marketing-page minute.
Solo developer: minutes — one CLI command provisions a mailbox and tunnel, and the quickstart sends a first email and places a first call. Support engineer: under an hour to add a dedicated VoIP number, contact rules, and vault secrets. Platform lead: an afternoon to roll out 100 identities, Slack connectivity, and MCP identity selection.
Switching to or from Inkbox
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From Twilio plus SendGrid: point your sending and receiving logic at Inkbox email and phone APIs, then retire the separate credentials per agent.
- →From a single shared inbox: call the identity API per agent to split into separate mailboxes, tunnels, and handles.
- →From a custom iMessage bridge: move to shared or dedicated iMessage numbers and keep the recipient list as contacts with sending permission.
- →From a manual secret store: import API keys and TOTP secrets into the zero-knowledge vault and grant per-agent access.
- →From Zapier-style glue: replace per-step connectors with the unified webhook subscription covering email, SMS/MMS, iMessage, calls, and A2A.
- ↗To Twilio plus SendGrid: re-implement each channel against separate provider APIs, losing shared identity, permissions, and cross-channel memory.
- ↗To a plain business phone line: export the number and rebuild messaging without per-agent handles or the tunnel endpoint.
- ↗To a self-hosted messaging stack: reproduce mailboxes, tunnels, contact visibility, and the credential vault on your own infrastructure.
- ↗To a single-channel chat API: accept that inbound email, PSTN calls, and iMessage no longer reach the same agent handle.
- ↗To a bespoke agent framework: reconstruct A2A brokering and the permission model rather than using the hosted broker.
Integrations
Resources & Guides
- Documentationinkbox.ai
Introduction · Inkbox
Full product docs from inkbox.ai
- Quickstartinkbox.ai
Quickstart · Inkbox
Get up and running fast from inkbox.ai
- Documentationinkbox.ai
Agent Signup · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Identities · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Email · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Phone · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Imessage · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Tunnels · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Contacts · Inkbox
Full product docs from inkbox.ai
- Documentationinkbox.ai
Vault · Inkbox
Full product docs from inkbox.ai
Tutorials & Learning
YouTube returned 6 videos for “Inkbox”, and we withheld 6: 6 could not be judged, because “Inkbox” is a single word that other videos use for other things. We are showing none, because we could not prove any of them are about Inkbox.
Official links
Featured Head-to-Head Comparisons
Inkbox vs Spider Cloud
Inkbox and Spider Cloud solve completely different problems. If your AI agents need to send/receive emails, SMS, iMessage, or handle phone calls with persistent identity, Inkbox is your only plug-and-play option. If your agents need to crawl the web at scale for RAG data, Spider Cloud delivers faster and cheaper with its Rust engine. Choose based on need—communication vs. data ingestion.
Inkbox vs Presto Voice
Presto Voice and Inkbox serve completely different purposes: Presto Voice is a specialized drive-thru voice AI for QSR chains, focusing on order automation and upselling, while Inkbox is a developer-oriented identity layer for AI agents needing multi-channel communication. Choose Presto Voice if you operate a QSR drive-thru and want to boost revenue and efficiency; choose Inkbox if you are building AI agents that need email, phone, or iMessage capabilities.
Inkbox vs Temporal Ai
Choose Temporal AI if your priority is building fault-tolerant, long-running workflows or AI agents that survive crashes and need orchestration. Choose Inkbox if your agents need a persistent identity with email, phone, and iMessage communication channels. They solve different problems; consider using both together for a reliable, communicative agent.
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