It is the file that will contain the recipients for the campaign when Operation Mode is FULL or SEND:

111;1;2;4;FieldUndefinedInMailupAccount1;FieldUndefinedInMailupAccount2
email1@mailup.com;John;Doe;Male;Dear;Friend
email2@mailup.com;Jane;Doe;Female;Distinguished;Madam
email2@mailup.com;Mark;Key;Male;Distinguished;Sir