Subscriber Emails Not Being Sent

Hello,

I have a client on my multisite install that is using the Subscribe by Email plugin. When they publish a new post, it is not being sent to the subscribers. There are less than 10 subscribers on their list.

When I check their logs, all the post say "Pending". I attempted to send the latest post manually. It now says "Finished", but their are no emails listed in the "Email details" section at the bottom of the details page, and I did not get the email.

Thanks,
Chris