The name of any CSV file to be uploaded to your MailUp account must follow one of the following two file naming conventions.

List_Number + Date/Time

<List_Number>_<yyyyMMddhhmmssffff>.csv

...where:

• • <List_Number> = the list number within your account (you can see it in your MailUp admin console)
  • <yyyyMMddhhmmssffff> = date and time when the file was generated, down to the millisecond

For example: 

3_201105031527211234.csv

List_GUID + Date/Time

<List_GUID>_<yyyyMMddhhmmssffff>.csv

...where:

• • <List_GUID> = unique identifier for the list in the MailUp system. It can be seen in the MailUp admin console under Settings > Edit Lists or retrieved via API by using the MailUpSend.GetListIdentity() method.
  • <yyyyMMddhhmmssffff> = date and time when the file was generated, down to the millisecond

6418A557-2335-4E7C-B620-5A66B7C8F977_201105020805060203.csv