If you upload Contacts into Sentori we automatically create a grouping (which we call an upload group) that you can use when sending your email. When you schedule your email all the Upload Groups will appear in reverse date order (newest first) as an option to send your email to. If you choose to send to an Upload Group, only the Contacts who were in that specific file upload will receive your email, less anyone that's since unsubscribed.
Upload Groups are a great way to work with adhoc or CRM-managed data; for example, a spreadsheet of Contacts that you met at a trade a show that you wish to send a “nice to meet you” type email. This is a one-off send and the Upload Group is a means to identify them as a segment.
If you have a CRM system that manages all of your Contact data and is being used to identify and create segments of Contacts, then Upload Groups are a good fit too. Have your CRM system export your chosen Contacts as a CSV file and then just upload them into Sentori. You'll then be able to email them by choosing the Upload Group when you schedule your email.
You may wish to view your Upload Groups and you'll find a link to them on the contacts homescreen.