How to Connect 1CRM with MailerCheck (2026)

Why Connect 1CRM and MailerCheck

1CRM is an all-in-one customer relationship management platform that combines sales management, marketing tools, project tracking, customer service, and order management in a single system. It provides contact and account management, email campaigns, invoicing, and workflow automation for small and mid-sized businesses. MailerCheck is an email verification and list cleaning service that validates email addresses to identify invalid, disposable, role-based, and risky addresses, helping businesses protect their sender reputation and improve email deliverability.

Connecting 1CRM and MailerCheck ensures that every email address in your CRM database is verified and deliverable. Over time, CRM databases accumulate invalid email addresses from typos during data entry, abandoned mailboxes, company domain changes, and contacts who have left their organizations. Without regular verification, sending to these addresses results in bounces that damage your sender reputation and reduce the effectiveness of your email outreach.

By integrating MailerCheck with 1CRM, you automate the process of validating email addresses as they enter your CRM and periodically re-verifying existing contacts. This keeps your CRM data clean and your email marketing effective, with higher deliverability rates and more accurate engagement metrics.

What This Integration Does

Linking 1CRM's contact management with MailerCheck's verification service enables several data quality workflows:

• Real-Time Entry Verification: Automatically verify email addresses when new contacts are added to 1CRM, flagging invalid addresses before they enter your active database.
• Bulk List Cleaning: Periodically export 1CRM contact lists to MailerCheck for bulk verification, then update contact records with verification status to identify addresses that need attention.
• Automated Status Tagging: Add verification status tags or custom field values to 1CRM contacts based on MailerCheck results, making it easy to filter and segment contacts by email quality.
• Pre-Campaign Verification: Verify email addresses in targeted 1CRM campaign lists before sending, removing invalid addresses to protect deliverability and improve campaign performance.

Native Integration vs Third-Party

1CRM and MailerCheck do not have a native integration. To connect them, you will need to use a third-party automation platform or build a custom integration using their APIs. 1CRM offers a REST API for managing contacts, accounts, and custom fields. MailerCheck provides both single-email and bulk verification API endpoints.

Zapier can handle simple workflows like verifying a new contact's email when it is added to 1CRM. Make offers more flexibility for batch processing and conditional logic. n8n is a good self-hosted option for teams that want to keep CRM data within their own infrastructure. For businesses with large contact databases, a custom script that runs on a schedule to process bulk verifications through MailerCheck's API and update 1CRM records is often the most efficient approach.

Step-by-Step Setup

Here is how to set up email verification for your 1CRM contacts using MailerCheck.

Step 1: Prepare Your 1CRM Custom Fields

In 1CRM, create custom fields to store verification data. Add fields such as email_verification_status (with options like Valid, Invalid, Risky, Unknown), verification_date (date field), and email_risk_score (number field). These fields will be populated by the MailerCheck integration and used for filtering and segmentation.

Step 2: Set Up API Access

Configure API access for both platforms. In 1CRM, enable the REST API and create API credentials with permissions to read and update contact records. In MailerCheck, log in and find your API key in the account settings. Test both API connections independently to confirm they are working.

Step 3: Build the Verification Workflow

Create an automation workflow that triggers when a new contact is created or when an existing contact's email is updated in 1CRM. The workflow should send the email address to MailerCheck's single-email verification endpoint, wait for the result, and then update the corresponding 1CRM contact record with the verification status and date.

Step 4: Set Up Bulk Verification

For your existing contact database, create a scheduled workflow that exports unverified or stale contacts from 1CRM, submits them to MailerCheck's bulk verification endpoint, and updates the records with the results. Schedule this to run weekly or monthly depending on the size of your database and how frequently contacts are added.

Step 5: Create Verification-Based Segments

In 1CRM, set up saved searches or dynamic lists that filter contacts by their email verification status. Create segments for verified contacts (safe to email), risky contacts (require review), and invalid contacts (should not be emailed). Use these segments to control which contacts receive email campaigns.

Common Use Cases

• Sales Outreach Quality: Verify email addresses of new sales leads before your team begins email outreach sequences, ensuring that follow-up emails actually reach the intended recipients and are not wasted on invalid addresses.
• CRM Data Hygiene: Run quarterly bulk verifications of your entire 1CRM contact database through MailerCheck to identify and clean out email addresses that have become invalid since they were first entered.
• Campaign List Preparation: Before launching email campaigns from 1CRM, run the target list through MailerCheck to remove invalid and risky addresses, protecting your sender reputation and improving open and click rates.
• Import Validation: When importing contact lists from trade shows, purchased lists, or data migration from another CRM, run all email addresses through MailerCheck before adding them to 1CRM.

Tips and Best Practices

• Verify email addresses at the point of entry into 1CRM rather than waiting for a batch process. This prevents invalid addresses from being used in sales outreach before they are caught.
• Set up 1CRM workflow rules that prevent contacts with "Invalid" email verification status from being added to email campaign lists, creating an automatic safeguard against sending to bad addresses.
• Re-verify contacts that have not been checked in the last 90 days, as email address validity can change over time due to domain changes, account closures, or full mailboxes.
• Track the source of invalid email addresses to identify which data entry channels or lead sources produce the lowest quality contacts, and address the root causes.
• Use MailerCheck's risk categories to create a tiered approach — immediately remove invalid addresses, flag risky ones for manual review, and keep only verified addresses in active campaign lists.
• Monitor your MailerCheck API usage against your plan limits, especially during bulk verification runs, and optimize batch sizes to stay within your allocated verifications per month.