The CSV file must contain a header row that maps the values contained in that column to a corresponding field in the MailUp system. In MailUp there are:
Some special fields that are reserved for e-mail, mobile phone number, and mobile phone number + country code.
Customizable personal data fields. Personal data fields (e.g. first name, last name, etc.) have a numeric ID that goes from 1 to 39 (it could be less than 39 for some subscription plans, please ask if you need an uprgade to 39).
MailUp contains the following special fields, which cannot be modified.
Mobile phone number's country code
Mobile phone number
Complete mobile phone number (country code + number)
A file to be imported shall contain a header row and one record for each recipient to be imported. The '|' (pipe) symbol is used as a separator and each row must contain exactly the same number of columns.
Basically, as soon as you respect the rules above, you are free to choose the type, order and number of columns you prefer. In this paragraph you can have a look at some examples,
Subscription on Email channel
Let's say that your CSV file contains these columns:
Date of Birth
*MailUp personal field ID or special field ID (refer to previous table for special fields)
This is an example of the file content
Use 111 in the header row for the email address. For the other columns use the ID of the corresponding field in MailUp.