URL Change Results in Email not being Sent

I've edited the URL of a subdomain on our Multisite install, and now emails aren't being sent.

The Sent Emails list is reflecting users who were previously subscribed to the old blog but have since been deleted. Those names are not appearing in the Subscribers list anymore, but according to the Sent Emails page, they were the only users who an email was successfully sent to.

The new subscribers, who subscribed since the URL was changed, are resulting in a User Content Empty error under the Sent Emails field.

Additionally, when I send a test email, the URL reflected in the no-reply@URL email address is the old URL, and not the new one.

Please let me know if you require additional info. I recognize this is an odd one.