Use a text editor (like Notepad++ or VS Code) or a Python script to remove duplicate entries.
Do not load the entire 150k file into RAM. Use a stream reader to process it line-by-line. 150k mailaccess.txt
If the list includes "last login" or "signup date," prioritize the most recent users to reduce bounce rates. 3. Verification and Hygiene Use a text editor (like Notepad++ or VS