We use a cloud based email security scanning service called GFI Max Mail Protection and on the whole this is a well priced and effective service. But recently my MD noticed that he no longer received his daily digest emails from the service.
I looked at the log files and I could see that his digest emails were being dropped with a NDR in the log files of 518.104.22.168 Message rejected as spam by Content Filtering.
I placed a support call as I couldn't think why his emails would be dropped as we use this is a our sole email scanning service, but it was a busy day and I didn't give it as much attention as I should have.
I get a email back from the GFI helpdesk to say, its my server that is dropping the emails, they checked their logs and could see my Exchange 2007 Server making the drop. A quick think and of course Content Filtering is part of Exchange 2007 Anti Spam features and naturally it was switched on!
This feature uses an algorithm to filter emails and it was seeing the digests as spam, probably because the digest contains HTML links to the emails so you can filter them manually. I quick switch off of this filter and my digests are being delivered again, which goes to show you should always have a good think on an issue before you fire off an email to the helpdesk!