Importing Subscribers from a CSV
If you already have a list of opted-in subscribers - in a spreadsheet, exported from another platform, or in your CRM - you can bring them into Mailblast with a CSV import.
A quick warning before you start: only import subscribers who knowingly signed up to hear from you. Importing a purchased or scraped list is the fastest way to get your AWS SES account suspended. See Why you should not send to purchased lists.
CSV format
Your file should be a standard CSV with a header row. Mailblast looks for three columns by name:
| Column | Required | Header names recognised |
|---|---|---|
| Yes | email or emails | |
| First name | No | first_name, firstname, first name |
| Last name | No | last_name, lastname, last name |
Example:
| first_name | last_name | |
|---|---|---|
| ada@example.com | Ada | Lovelace |
| grace@example.com | Grace | Hopper |
Any other columns in your CSV are ignored on import - Mailblast only stores email, first name, and last name on each subscriber. See Merge fields for the full list of personalisation fields available in campaigns.
Import a CSV
Go to the Lists page in your account, open the Action menu on the list you want to import into, and select Import Subscribers. Upload the file and Mailblast processes it in the background, showing you progress as it goes.
What happens to duplicates
If an address in your CSV already exists on the list, Mailblast updates that subscriber's first and last name fields rather than creating a duplicate. The existing subscription status (active, unsubscribed, bounced) is preserved - re-importing an updated CSV will not resurrect someone who has unsubscribed.
Imported subscribers and double opt-in
Imported subscribers are added directly as active - they do not go through the double opt-in verification flow, even if you have it enabled on the list.
This is the right behaviour when you are moving over a list that was already opted in on another platform. If you cannot verify that your imported subscribers genuinely opted in, do not import them - get fresh consent through your signup form instead. See Why you should not send to purchased lists.
Ongoing syncing
The CSV upload is intended for one-shot list migration. If you need ongoing automated syncing with another system, use the API or a Zapier integration instead.