How to use regex to filter and clean thousands of email addresses
Email & Newsletters, Automation & No-Code, Analytics & Optimization
This task explains a practical approach to using regular expressions to clean large email lists. It focuses on accuracy, performance, and repeatable steps.\n\nDefine a realistic regex, test it on sample data, then apply filtering to remove bad addresses and duplicates.\n\nDocument the rules and export a cleaned list for downstream use.
Who is this for?
- Data engineers\n- Marketing teams\n- Operations or data cleanup specialists\n- Customer support teams
Before you start
- Basic regex knowledge\n- Sample dataset\n- Access to data export
General Process (How it works)
- Define the goal and data source Identify where emails come from, what quality issues exist, and what needs filtering.
- Choose a robust email regex pattern Select a pattern that matches common email formats and excludes obvious invalid forms.
- Test the pattern on sample data Run tests with a small subset and adjust for edge cases.
- Apply filtering to remove invalid addresses Filter out non-matching results and highlight near-misses.
- Normalize and deduplicate Trim whitespace, unify case, and remove duplicates.
- Validate with real-world data Sample a larger dataset and verify results.
- Document rules and export results Capture the regex, rules, and export cleaned list.
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