I have a leads table with 5k rows. I ran email enrichment through an external API, and the vendor sent back a CSV with 1,000 verified emails.

You can use Google Sheets as an intermediary to merge the data. Import your CSV with verified emails to Google Sheets, then use Clay's Google Sheets integration to lookup and add the emails to your existing table using the shared key. [clay.com Alternatively, you can use Clay's 'Merge column' feature which works with a waterfall priority system to consolidate data from multiple sources. For the smoothest workflow, I'd recommend trying Sculptor (our built-in AI tool in the top-right corner) - it can help you set up the exact automation you need for this merge process.