withoneai Mailbox Validator through One
MailboxValidator provides real-time email address verification and list-cleaning services—via easy RESTful APIs or bulk uploads—to detect invalid, disposable, free, role-based and unreachable emails, helping businesses reduce bounce rates, improve deliverability, and maintain higher-quality marketing data.
One exposes Mailbox Validator through four MCP tools. The table below carries real action ids from One's knowledge base, so for a common operation you can skip search and go straight to reading the action's parameters.
How to run an action
- Find the action in the table below, or call
search_one_platform_actionswith platformmailbox-validatorif it is not listed. - Call
get_one_action_knowledgewith the action id. Do this every time, including for actions in this table. The table gives you the id, not the parameters. - Call
execute_one_actionwith parameters copied from that knowledge.
Never guess a parameter name, a body field, or an enum value. The knowledge has the real schema, and a guessed field is either a 400 or a silent write of the wrong thing.
Before you start
Call list_one_integrations once and confirm Mailbox Validator is connected. If it is missing, the user has not connected it: say so and point them at https://app.withone.ai rather than reaching for raw HTTP.
Each connection carries an access field. If it reports {"policy": "methods", "methods": ["GET"]} the agent is read-only here, so plan a read-only answer instead of attempting a write that will be refused.
Before a write
Creates, updates, deletes and sends land on a real Mailbox Validator account and cannot be recalled. State the action and the specific target in one line before the first write in a task, and let the user stop you. Reads need no confirmation.
Actions
EmailValidation
| Action | Method | Path | Action id |
|---|---|---|---|
| Test Connection | GET | /v2/validation/single?email='test' |
conn_mod_def::GJd9wr5yUbA::vxIyfL1OQL2bqEjeq8q60g |
| Validate a Single Email Address | GET | /v2/validation/single |
conn_mod_def::GJd7D2uuxCg::MxQG0BWySJ20sHHOU_RqtA |
EmailDisposable
| Action | Method | Path | Action id |
|---|---|---|---|
| Check if an Email Address Is Disposable | GET | /v2/email/disposable |
conn_mod_def::GJd7D9htb2A::g4fHV2T6QP2pyuhk20Xjcw |
EmailFreeProviderCheck
| Action | Method | Path | Action id |
|---|---|---|---|
| Check if an Email Address Is from a Free Email Provider | GET | /email/free |
conn_mod_def::GJd7EFdxE0g::foxiQOTTTpCkdjHJIoX5SA |
When a call fails
The error comes from Mailbox Validator, not from One. A 400 or 422 means your parameters do not match the schema, so re-read the knowledge and fix the field. A 401 or 403 means the connection needs re-authorizing, which no retry will fix. A 404 means the id is not on this account. A 429 means slow down. Never retry a write more than once: the first attempt may have landed.
Full catalog: https://www.withone.ai/knowledge/mailbox-validator
Integration knowledge by One (withone.ai), licensed under One-Knowledge-1.0. Attribution must be preserved in derivative works.