10,000 entries. This is a substantial "starter" size for a campaign, allowing for statistically significant A/B testing.
Convert the .txt to a .csv to better manage any associated metadata (names, locations, etc.) that might be hidden in the strings. 10K MIX MAIL ACCESS .txt
High-volume cold outreach or top-of-funnel awareness. 10,000 entries
The "MIX" label implies a diverse range of domains (e.g., Gmail, Yahoo, Outlook) or perhaps a mix of consumer (B2C) and professional (B2B) leads. 10K MIX MAIL ACCESS .txt
Plain text (.txt). While universally compatible and easy to import into most CRM or email marketing tools, it lacks the structured organization (like headers or columns) found in CSV or Excel files. 2. Content Composition ("Mix")