Within Send, it is possible to find out which Group a Contact is from when a list of contacts have been exported as an XLS or CSV file.
The first step to achieving this is to download a Contacts list. You can do this by selecting Contacts from the main selection bar.
Once in to the Contacts section, navigate to the Groups tab, where you are presented with all of your contact groups. Now to export your Contacts list, click the blue drop down arrow to the right of the desired contact group and select either Export Contact as CSV or Export Contacts as XLS.
Alternatively, you could click into the Contact group, navigate to the drop down arrow on the left hand side of the page and select either Export CSV or Export XLS.
Once the Group Contact list has been downloaded, you can find the Group in which each Contact exists in the Groups column towards the far right of the spreadsheet.
If a Contact is in more than one than one Group, all their Groups will be listed (separated by a comma) in the Groups column when exported.