What should I clean before importing a list to a CRM?

At a minimum: remove duplicate rows, normalize email addresses (lowercase and trim), standardize phone numbers to E.164, split full names into first and last fields, fix the header row, check required fields, and confirm character encoding is UTF-8. Doing these seven things prevents the most common import failures.

Why do CRM imports fail so often?

Most failures come from predictable data problems: duplicate rows that create duplicate contacts, malformed emails or phones that fail validation, a single name column when the CRM expects first and last separately, and encoding issues that turn accented characters into mojibake. Cleaning the file first removes those failure points.

Do I need to clean the data before import, or can the CRM do it?

Some CRMs offer light cleanup on import, but they cannot reliably split names, normalize phones to E.164, or merge near-duplicates that differ in case or spacing. It is faster and safer to clean the spreadsheet first so only valid, deduplicated rows reach the system.

Can I run this whole checklist without uploading my file?

Yes. Each Sigmera tool — duplicates, emails, phones, and names — runs entirely in your browser, so your contact list never leaves your device. That keeps personal data GDPR-safe by design because nothing is sent to a server.

The data cleaning checklist before any CRM import

Published June 1, 2026 · Last updated: June 2026

Before importing a spreadsheet to a CRM, run seven checks: remove duplicate rows, normalize emails, standardize phone numbers to E.164, split full names, fix the header row, confirm required fields, and verify UTF-8 encoding. Each one heads off a common import failure — and all of them can be done in your browser without uploading the file.

The seven-point checklist

Work through these in order. The first four are the ones that most often cause a CRM to reject rows or create duplicate contacts, and each has a dedicated tool that runs locally in your browser.

1. Remove duplicate rows

Duplicates inflate your counts and create two records for one person. Dedupe on the email or phone column, and decide whether to keep the first or last copy of each match, before anything else.

Remove duplicates from CSV

2. Normalize the email column

Lowercase everything, trim leading and trailing spaces, and drop rows that fail a basic syntax check (the local-part and domain rules from RFC 5322). Clean emails import cleanly and deduplicate properly.

Clean email column

3. Standardize phone numbers to E.164

Convert messy numbers to the E.164 international format — +, country code, national number, up to 15 digits, no spacing. CRMs and SMS tools require it, and it makes phones deduplicate reliably.

Clean phone numbers

4. Split full names into first and last

Most CRMs store first and last name in separate fields. Split a single “Full Name” column into first and last (with an optional middle name) so personalization tokens like {{firstname}} work.

Split full names

5. Fix the header row

Make sure the first row holds clean, unique column names that map to CRM fields — no merged cells, no blank headers, no duplicated labels. This is what the import wizard reads to build its mapping.

6. Check required fields

Identify the fields your CRM marks required (often email or a name) and confirm none are blank. Rows missing a required value are the most common reason an import partially fails.

7. Confirm UTF-8 encoding

Save the file as UTF-8 CSV so accented and non-Latin characters survive. A file saved in a legacy encoding turns names like “José” into garbled text once imported.

A quick reference

Check	Prevents	Tool
Duplicates	Duplicate contacts	Remove duplicates
Emails	Validation failures	Clean email column
Phones	Rejected / unroutable numbers	Clean phone numbers
Names	Broken personalization	Split full names

Run the whole checklist in your browser — nothing uploaded to a server.

Start with duplicates Related topic: cleaning email lists

Frequently asked questions

What should I clean before importing a list to a CRM?: At a minimum: remove duplicate rows, normalize email addresses (lowercase and trim), standardize phone numbers to E.164, split full names into first and last fields, fix the header row, check required fields, and confirm character encoding is UTF-8. Doing these seven things prevents the most common import failures.
Why do CRM imports fail so often?: Most failures come from predictable data problems: duplicate rows that create duplicate contacts, malformed emails or phones that fail validation, a single name column when the CRM expects first and last separately, and encoding issues that turn accented characters into mojibake. Cleaning the file first removes those failure points.
Do I need to clean the data before import, or can the CRM do it?: Some CRMs offer light cleanup on import, but they cannot reliably split names, normalize phones to E.164, or merge near-duplicates that differ in case or spacing. It is faster and safer to clean the spreadsheet first so only valid, deduplicated rows reach the system.
Can I run this whole checklist without uploading my file?: Yes. Each Sigmera tool — duplicates, emails, phones, and names — runs entirely in your browser, so your contact list never leaves your device. That keeps personal data GDPR-safe by design because nothing is sent to a server.