This feature allows to import contacts and send text messages in one single operation. You can deposit your .CSV file on a shared repository on MailUp servers: this file must contain all the required information for sending (e.g. sender, date and time of sending, body of the text message, recipients, and so on).
This feature was designed for handling files containing several hundreds or several thousands of recipients with a single file and no more than one file in a minute. If you are planning to develop an integration with an higher upload frequency or with smaller files, we recommend you consider using transactional APIs for SMS instead.
Please ensure you save your file using UTF-8 encoding (with BOM), otherwise extended ASCII characters (e.g. accented letters, non western alphabets...) may be corrupted.