Import contacts from a CSV file

If you already have a list of subscribers in a spreadsheet, you can bring them all into Mailbo at once with a CSV import. Mailbo de-duplicates by email automatically, so re-importing won't create copies.

Before you start: prepare your file

1. Open your spreadsheet (Excel, Google Sheets, etc.).
2. Make sure the first row is column headers — e.g. email, first_name, last_name, company.
3. Every contact needs an email in one of the columns.
4. Export / save as CSV (in Google Sheets: File → Download → Comma-separated values).

Limit: up to 50,000 rows per import. If your file is bigger, split it into several files and import them one after another.

Step 1 — Open the importer

1. Click Contacts in the left menu.
2. Click Import (or go to Contacts → Import).

3. Click the Click to upload CSV box and choose your file.

Step 2 — Map your columns

After uploading, Mailbo shows your columns next to its own fields. For each column, tell Mailbo what it is:

• Point your email column at Email (required).
• Point name columns at First name / Last name.
• Map any other columns to a custom field, or leave them unmapped to ignore them.

Step 3 — Tag or list the import (recommended)

Assign a tag or add everyone to a list during import — e.g. tag them imported-jan-2026. This makes it easy to find or email exactly this batch later.

Step 4 — Import

Confirm and start the import. Mailbo adds new contacts and updates existing ones (matched by email) — no duplicates.

Good to know

• Imported contacts are added as Subscribed and skip double opt-in (you're vouching that they agreed to hear from you).
• Only import people who actually opted in. Importing bought or scraped lists will wreck your deliverability and may get your account suspended.

Next: Tags vs Lists · Segment your audience