Unknown Sender on Subscribe by Email Plugin

I am using the latest version of Subscribe via Email on the latest version of WP Multisite. When I updated to the most current version of the plugin (3.2.1), my emails that are being sent out come from "unknown sender". When the plugin was on the older version (2.4.3), everything was fine.

How can I put in a default sender name that shows up pretty in gmail and other inboxes?