The error "the following columns must be specified: Sender e.212" occurs while importing rates when the flag "Use sender MCCMNC based rates" is selected in the product (Start\Carriers\Products).
If routing by sender MCCMNC is not required, you may deselect this flag - but to do so, all rates (including inactive) must be removed from the product.
AKBSMS - Alaris Knowledge Base
Related Questions:
The following columns must be specified: Sender e.212
The Sender e.212 column
Link to this article: https://helpdesk.alarislabs.com/en/knowledge_base/category/138/