FTP Voyager Scheduler Email

Hello,

I've been using FTP Voyager for a little over a year now. My event email notifications have always worked. All of the sudden about a month ago the email notifications come form Voyager have been sporadic and then not at all. I don't see anything wrong with my SMTP server seeing as everything else is coming through it (such as my web filter, firewall and other server notifications). It is only notifications from FTP Voyager. Is this a known error?

Thanks.