Import contacts from CSV

Import the attached CSV of 347 leads from the June tradeshow. Map CSV columns to contact fields: Full Name to Name, Email to Email, Phone to Phone, Company to Company, Job Title to Job Title, Lead Source set to Tradeshow-June, Owner default to Sofia Alvarez, and Tags add Tradeshow2026. Validate emails, skip rows with invalid emails, and produce a summary of imports and skipped rows once complete.

Before I import 347 tradeshow leads, make the file import-ready: surface duplicate risks at the top, show estimated updates vs. new records based on email, make lead source obvious so it won't be overwritten, and flag rows with missing emails or malformed phone numbers. Also highlight any contacts that would change owner from someone outside our sales team.

I started the tradeshow import and the preview shows 120 existing records will be updated. I expected most to be new leads. I'm concerned the update rule based on email will overwrite owners or notes on those existing records. I can't tell which fields will be updated or whether notes will be preserved. What's the likely reason so many are matching existing records, and what safe import settings should I choose to avoid losing critical owner or note history?

Bulk imports keep changing owners and wiping call notes because we use blanket update rules. That forces manual rollbacks and corrodes trust with sales. Which import habit should I change so imports add missing data without overwriting ownership or activity, and what default import mapping would save us the most time across future events?