Jetpack uses your site title as the sender name, but the sender information can be overwritten by your mail client, if you have created a contact matching the sender email address.
Could you check your Thunderbird Contact settings? You may have created a new contact named "ASDUpdates", matching all emails sent from WordPress.com. If you find this contact, you will need to remove it so your email client can use the information provided by Jetpack:
- MountainCreekTownhouses.info WordPress Blog
- ASDUpdates.com