Importing contacts from CSV or Excel without breaking anything

Importing a poorly prepped list is the number one cause of problems in early sends: names in the wrong column, duplicates, invalid addresses that bounce. The good news is that 90% of those problems are avoidable before you import, just by tidying up the file.

A CSV (or an Excel file) is simply a spreadsheet: each row is a contact, each column a piece of data (email, name, city). This guide takes you from a messy spreadsheet to a clean list ready to segment.

1. Tidy up the file before touching arrobaMail

Most import errors are born in the file, not the platform. Open your CSV or Excel file and check these basics:

• One column per piece of data. Email in its own column, first name in another, last name in another. Don't cram "John Smith [email protected]" into a single cell.
• Clear headers in the first row. email, name, city… That way it's easy to indicate which column is which later.
• A single sheet. If it's Excel, keep the data on one tab, no pivot tables or totals at the bottom.
• No decorative rows. No titles, logos, or blank rows above the headers.

The email column is the only required one; everything else is optional data that will help you personalize and segment down the line.

Tip: if you're exporting from another tool (a store, a CRM, an old spreadsheet), choose the "CSV UTF-8" option when saving, if it's available. That's what keeps accented characters from breaking during import (so you don't end up with things like "Jos Garca" instead of "José García").

2. Clean the data: duplicates, blanks, and formatting

Cleaning before you import is a lot easier than fixing it afterward. Spend five minutes on:

• Removing duplicates. In Excel or Google Sheets, use "Remove duplicates" on the email column. Repeated addresses inflate your list and can cause duplicate sends.
• Deleting rows with no email, or with obviously invalid ones (missing @, containing spaces, or things like "test" or "donotsend").
• Normalizing case and spaces. Lowercase all emails and trim leading or trailing spaces (the TRIM function helps).
• Reviewing names and other data you plan to use for personalization: if you're going to write "Hi {name}," make sure the name column doesn't have last names stuck on, or oddly empty cells.

It doesn't need to be perfect, but the cleaner it goes in, the better you'll be able to segment and the fewer bounces you'll see.

3. Create the list and custom fields

In arrobaMail, contacts live inside a list. Create one with a name you'll recognize (for example, "Customers 2026" or "Newsletter subscribers").

If, beyond email, you want to store other data (name, city, customer type, signup date), define them as custom fields. These become the "columns" each contact has, and beyond personalizing your messages, they're the foundation of segmentation: later you'll be able to send only to "customers in Austin" or "anyone who's ever bought."

Think about what data you'll actually use. You don't need to load everything — just add the fields that help you personalize or segment.

4. Import and map the columns

With the list and fields ready, upload the file. The key step is matching each column to its data (what's called "mapping"): arrobaMail shows you your file's columns and you tell it what each one is (this column is "email," this one is "name," this one is "city").

Take your time reviewing the mapping — it's where the classic mistake of loading the last name into the first-name field tends to sneak in. If there's a column in the file you don't want to import, leave it unassigned.

Tip: if this is your first import with a large file, try it first with a sample of 10–20 rows. Confirm the mapping came out right, and only then upload everything.

5. Review the results: imported, bounced, and rejected

Once the import finishes, arrobaMail shows you a summary: how many contacts made it in, how many were left out, and why. Pay attention to:

• Rejected for format: invalid emails the system caught. These are usually typos in the original file.
• Duplicates: if any showed up, they get merged — they don't load twice.
• Bounces (later on): after your first send, you'll see addresses that bounce (because they don't exist). Remove them — a list with a lot of hard bounces hurts your reputation.

Don't be alarmed if fewer contacts make it in than you expected: a list of 800 valid addresses beats one of 1,000 with 200 invalid ones.

6. Protect permission and keep up ongoing hygiene

A list doesn't get imported once and forgotten — it needs care. Two habits worth their weight in gold:

• Real permission. Only import contacts who agreed to hear from you. If you're unsure about part of the list, consider a confirmation campaign before sending to it in full.
• Ongoing hygiene. Every so often, remove hard bounces and check who hasn't opened in months. A healthy, engaged base delivers better than a large, dead one — AI-powered filters look at exactly that.

If you want to dig into why cleanliness matters so much for delivery, check out why your emails end up in spam.

Common mistakes to avoid

• Importing without cleaning first. "I'll fix it later" turns into sends with an empty "Hi {name}" and avoidable bounces.
• Mismapping the columns. Double-check the mapping step — it's the easiest one to get wrong.
• Loading purchased lists. It's not just bad practice — it burns your reputation from the very first send.
• Forgetting UTF-8. Broken accented characters ("Jos Garca") scream amateur.

Next steps

With your list clean and loaded, you're ready to:

1. Create and send your first campaign.
2. Authenticate your domain so that campaign actually lands → SPF, DKIM, and DMARC.

Don't have an account yet? Create one for free and import your first list.