MailBluster doesn’t force you to upload your CSV file in any particular format, rather it’s flexible with any CSV file. You can select which column contains what data. For example – you can have a column in your CSV named “Subscriber name” and select it column as “First name” while importing in MailBluster.
Here is a sample CSV file with columns necessary for uploading leads to MailBluster. You can follow this to upload your data.
See the sample file on Google Sheets.