--- title: "MailerCheck Integration" description: "MailerCheck is MailerLite's email verification and list cleaning tool. Agents verify addresses in real time or asynchronously, build verification lists from arrays or files, run them, read the results, and watch credits." url: https://flowrunner.ai/integrations/mailercheck date_modified: 2026-09-04T14:28:58-07:00 --- # MailerCheck [Email Marketing](https://flowrunner.ai/integrations/category/email-marketing) MailerCheck is MailerLite's email verification and list cleaning tool. Agents verify addresses in real time or asynchronously, build verification lists from arrays or files, run them, read the results, and watch credits. [Verified](https://flowrunner.ai/integrations/verified "What does verified mean?") · 13 actions · API key · available [MailerCheck website](https://www.mailercheck.com/) · [Platform Documentation](https://developers.mailercheck.com/) · Capability data verified 2026-08-19 1. The monthly hygiene job starts against a dormant segment 2. Create Email List builds the list from the segment, which costs nothing yet 3. Get Credit Balance is read against the row count before anything is spent 4. Start List Verification begins the run and is the moment the credits go 5. Get List Results reads the per address outcomes once the run has finished 6. Only the valid outcomes are cleared to send, the risky cohorts are held separately 7. The owner authorizes deleting the verified list once the results are exported ## What This Integration Enables MailerCheck is MailerLite's verification product, and the thing that shapes every workflow around it is that a list is a real object with a lifecycle. Building a list costs nothing. Uploading a file costs nothing. The list sits in a not-started state until Start List Verification runs, and that call is the moment credits are spent. The vendor's two refusal modes are worth knowing apart: a shortfall refuses the whole run rather than verifying part of it, and a second attempt against a run already under way is refused rather than charged twice. That second behavior is the safe direction, and it means the risk in this connector is never the retry. It is the composition of the list. The other thing that shapes the work is that MailerCheck does not give you a boolean. It gives eleven outcomes grouped three ways, and only one of them is send-to. The risky group includes catch-all domains, where the server accepts everything so nothing was proven, and role addresses, which are shared team mailboxes rather than mistakes. Treating those as failures throws away support@ and sales@ at every company you sell to. FlowRunner agents keep the groups apart, run the expensive step only when the balance supports it, and hold the destructive step behind a [human-in-the-loop](https://flowrunner.ai/concepts/human-in-the-loop) gate. ### Without FlowRunner **Eleven outcomes collapsed into two**: Everything that is not valid gets treated the same, so shared team addresses die alongside typos **Credits spent before anyone looked**: A run starts against a list nobody sized, and the shortfall shows up as a refusal mid-job **Results live only in the tool**: The per address outcomes stay in the verifier and get re-bought the next time someone asks ### With FlowRunner **Outcomes handled by group**: Send to, risky, and do not send are three different piles with three different next steps **The balance is read before the run**: The list is built for free, sized against the balance, and only then started **Results exported before cleanup**: The outcomes land in a durable store first, and deletion happens after, with permission ## Use Case Scenarios ### A re-engagement list that gets checked before it gets mailed A dormant segment is pulled from [MailerLite](https://flowrunner.ai/integrations/mailerlite) and the agent calls Create Email List with the addresses. Nothing has been spent yet, so the agent reads Get Credit Balance and compares it against the row count. If the balance covers the run, Start List Verification begins it. The agent polls Get Email List for the state, then pulls Get List Results and writes four cohorts to [Google Sheets](https://flowrunner.ai/integrations/google-sheets): valid, risky with the catch-all and role reasons separated, do-not-send, and error. The re-engagement campaign is built from the first cohort. The role addresses go to a different campaign written for a shared inbox rather than a person. ### Signup validation that does not make anyone wait A signup posts an address. Verify Email holds the connection open while the recipient's mail server is asked, and some servers deliberately make that slow, so the agent uses Start Async Verification instead and lets the person finish signing up. A moment later Get Async Verification reads the outcome. A valid result confirms the account. A typo result, which the vendor marks as fixable, produces a message asking the person to check the address rather than a hard rejection, and the agent re-verifies the correction. A disposable or blocked result routes to review in [Slack](https://flowrunner.ai/integrations/slack). ### A file that never has to be pasted anywhere An agency partner drops a CSV of event registrations at a URL. The agent calls Upload Email List, which fetches the file and forwards it, so nobody converts anything into an array by hand. Once the run has finished, the agent reads Get List Results filtered to the valid outcomes and writes them into [HubSpot](https://flowrunner.ai/integrations/hubspot) with the verification date on each record. The invalid rows are returned to the partner with their reasons attached, which is more useful to them than a count. ## Human-in-Loop Highlight Delete Email List is the operation this connector should never run on its own, and the reason is not that lists are precious. It is that the per address outcomes live nowhere else. Get List Results is the only route that reads them, and it reads them out of the list. Delete the list and the outcomes those credits bought are gone, with no restore operation anywhere in the API. A cleanup step that tidies away last quarter's lists is therefore quietly deleting evidence the account paid for, and the next hygiene run buys the same answers again. So the cleanup agent proves the export first and then asks. It posts: "Verification run on Dormant Q2 finished. 18,400 addresses: 14,100 valid, 2,600 risky (1,900 catch all, 700 role), 1,650 do not send, 50 error. All 18,400 rows exported to the hygiene sheet with their result codes. Delete the list in MailerCheck?" The marketing owner confirms, or asks for the list to be kept until the campaign has actually run. The agent is the right thing to run the verification and to move the results somewhere durable. Deciding when the only copy of a paid result can be destroyed belongs to the person who will be asked for it later. Agent processes routinely Detects exception requiring judgment Clear match Continues automatically Ambiguous Routes to human via preferred channel Human decides Agent resumes with decision ## Agent Capabilities 13 actions ### Verification 3 - **Verify Email** Checks one address in real time and returns one of the vendor's eleven outcomes, with safe and risky flags added by the connector so a flow branches on a flag rather than comparing strings. Holds the connection open while the recipient's mail server is queried. Used where the caller can wait, such as a back-office import. - **Start Async Verification** Queues one address for checking and returns an identifier immediately. Used on signup and checkout paths, where holding a person on a spinner while a slow mail server is asked is not acceptable. - **Get Async Verification** Reads the outcome of a queued check. While the check is still queued the result is empty rather than negative, so a flow polls rather than concluding. Used to complete the asynchronous path. ### Lists 7 - **List Email Lists** Returns every verification list with its status and per outcome statistics, paged. Used to find running jobs, to report on hygiene history, and to locate a list by name before acting on it. - **Get Email List** Reads one list including its start and end times. Used to poll a run for completion and to record how long a job took. - **Create Email List** Builds a verification list from an array of addresses. Costs nothing and leaves the list unstarted. Used as the first step of any segment hygiene run, where sizing the list before spending is the point. - **Upload Email List** Builds a verification list from a CSV or TXT file fetched from a URL. Used when the addresses already live in a file, or when there are too many to pass as an array. - **Start List Verification** Begins the run on a list. This is the operation that spends credits, and it is not reversible. A shortfall refuses the whole run rather than verifying part of it, and a run already under way is refused rather than charged again. Used once the balance has been read and the list has been sized. - **Get List Results** Reads the per address outcomes for a list, filterable by result. This is the only route that returns them, so it is also the export path. Used to build the cohorts a campaign and a suppression list are made from. - **Delete Email List** Removes a list permanently, along with the per address outcomes it holds. Not reversible. Used in cleanup, and only after the results have been written somewhere durable. ### Account 3 - **Get Account** Returns the account's details including its credit balance. Used for reporting and as a second read before a large run. - **Get User** Returns the user the API token was created by. The token is tied to both the user and that user's account, so this is how a flow confirms which account it is acting in. - **Get Credit Balance** Returns the credits remaining. Used immediately before Start List Verification, because a run that cannot be paid for is refused in full rather than partially completed. ## Frequently Asked Questions ### What can FlowRunner do with MailerCheck? FlowRunner agents can run Verify Email, Start Async Verification, and Get Async Verification in MailerCheck, plus 10 more actions. ### Does connecting MailerCheck to FlowRunner require OAuth? No. MailerCheck connects to FlowRunner with an API key, no OAuth flow required. ### Can MailerCheck trigger a FlowRunner workflow automatically? MailerCheck doesn't currently expose triggers in FlowRunner. It connects as an action step inside workflows started by another trigger. **Work at MailerCheck?** This integration exposes MailerCheck to AI agents on every FlowRunner plan, including through MCP, at no cost to you. [See what FlowRunner offers integration partners](https://flowrunner.ai/integrations/partners), including how to keep this page current. --- Markdown version of https://flowrunner.ai/integrations/mailercheck. Site index: https://flowrunner.ai/llms.txt