Get started

Unione for AI agents

UniOne sends transactional and marketing email through a web and SMTP API, used by product and marketing teams delivering emails at scale. Connect it once through Arc0, and your agent, or Claude, ChatGPT and Cursor, can use it through one MCP endpoint, limited to what each user approved.

Connect UnioneSee the 32 actions ↓
EmailAPI keyMCP + RESTunione.io
AUDIT LOG · UNIONEPOLICY: acme-support
09:41:07 · claude · u_8f2read
unione.get_webhook
Get Webhook Configuration✓ allowed · 212ms
09:41:08 · claude · u_8f2read
unione.get_template
Get Template✓ allowed · 164ms
09:41:09 · claude · u_8f2write
unione.tag_list
UniOne Tag List✓ approved · approved by user
09:41:12 · claude · u_8f2destructive
unione.delete_webhook
Delete Webhook✕ blocked · policy: deny
EVERY UNIONE CALL, ON THE RECORD
01 · USE CASES

What agents do in Unione.

01

Get email statistics

Pull send, open, and bounce statistics as a read-only report.

02

Check an email's delivery event

Look up the delivery status of a specific sent email.

03

Confirm before removing from the suppression list

Check with the user before removing an address from the suppression list, since that re-enables sending to it.

02 · ACTIONS

32 Unione actions, graded by risk.

Every Unione action is tagged read, write or destructive, so one policy covers the whole app and new actions inherit the right default.

read

4

Look things up. Allowed by default.

  • unione.get_webhook
    Get Webhook Configuration
  • unione.get_template
    Get Template
  • unione.get_event_dump
    Get Event Dump
  • unione.get_suppression
    Get Email Suppression Details

write

21

Create and change things. Allow, or ask the user first.

  • unione.tag_list
    UniOne Tag List
  • unione.email_get
    Get Email Send Job
  • unione.email_list
    UniOne Email List (Export)
  • unione.email_smtp
    UniOne Email SMTP Configuration
  • unione.webhook_set
    Set Webhook
  • unione.email_domain
    UniOne Email Domain Management
  • unione.email_resend
    Resend Sent Email
  • unione.email_resume
    Resume Paused Email
  • unione.template_set
    Set Template
  • unione.email_balance
    UniOne Email Balance
  • unione.template_list
    UniOne Template List
  • unione.schedule_email
    Schedule Email
  • unione.email_event_get
    Get Email Event
  • unione.event_dump_list
    UniOne Event Dump List
  • unione.email_statistics
    UniOne Email Statistics
  • unione.suppression_list
    Suppression List
+ 5 MORE

destructive

7

Delete, cancel or archive. Ask first, or deny outright.

  • unione.delete_webhook
    Delete Webhook
  • unione.delete_template
    Delete Template
  • unione.delete_event_dump
    Delete Event Dump
  • unione.tag_delete
    Delete Tag
  • unione.email_cancel
    Cancel Scheduled Email
  • unione.email_unsubscribe
    UniOne Email Unsubscribe
  • unione.email_validate_delete
    Remove Email from Suppression List
03 · HOW IT WORKS

Unione in three steps.

  1. 01Your users connect UnioneThey add their Unione api key on Arc0 Connect, under your brand. It goes straight into the vault.
  2. 02You set the rulesReads run, writes like “uniOne Tag List” can wait for the user, and “delete Webhook” can be denied outright.
  3. 03Any agent can actYour agent calls Unione through the Arc0 SDK or MCP, and so can Claude, ChatGPT and Cursor. Every call lands on the audit log.
POLICY.TS
await arc0.policies.set('unione', {
  read: 'allow',
  write: 'ask',        // tag_list
  destructive: 'deny',  // delete_webhook
})

# Claude Code: the same connection, one URL
$ claude mcp add --transport http arc0 \
    https://mcp.arc0.ai/u/u_8f2
04 · AUTH AND DATA

How Unione connects.

Users add their Unione api key on Arc0 Connect. It is encrypted in the vault, never shown to the model, and each user can rotate or revoke it at any time.

The same Unione connection serves your agent over MCP and your own backend over REST and the proxy, so a user connects once. How Arc0 handles credentials →

AUTH
API key
CREDENTIALS
Per-tenant encrypted vault
MODEL SEES
Results only, never credentials
AUDIT LOG
Every call, on every plan
05 · WORKS WITH

Use Unione from any agent.

Claude
ChatGPT
Cursor
Codex
VS Code
OpenAI Agents SDK
Claude Agent SDK
Vercel AI SDK
Mastra
LangGraph
06 · RELATED

More email apps.

Gmail62 actionsOutlook306 actionsSendGrid364 actionsMixmax94 actionsElastic Email91 actionsResend66 actionsLettr60 actionsPostmark46 actions
ALL EMAIL APPS →
07 · FAQ

Unione and Arc0, answered.

Q01

Can I use Unione with Claude, ChatGPT or Cursor?

Yes. Connect Unione to Arc0 once, then add your Arc0 MCP URL to Claude, ChatGPT, Cursor, Claude Code or any other remote-MCP client. Each assistant only gets the Unione actions you allow.

Q02

How do users connect Unione?

Users add their Unione api key on Arc0 Connect. It is encrypted in the vault, never shown to the model, and each user can rotate or revoke it at any time.

Q03

Which Unione actions can my agent take?

32 in total: 4 read, 21 write and 7 destructive, such as “uniOne Tag List”. Your policies decide which of them each agent may call.

Q04

Can I stop my agent from deleting things in Unione?

Yes. Actions like “delete Webhook” are graded destructive. Set destructive actions to deny, or to ask so the user approves each one, and blocked calls still show up on the audit log.

Q05

Can my own backend call Unione too?

Yes. The same Unione connection is available over REST and through the Arc0 proxy, so your product and your agent share one connection per user.

Get started

Plug Unione into your agent.

Your users connect Unione once, under your brand. Your agent gets 32 actions behind your policies, with every call on the record.

Connect UnioneBrowse all apps →

Free to build · MCP + REST · Audit log on every plan