Change to PennO365 will affect end user’s Junk experience


On Thursday, October 12, 2017 at 12:00pm, ISC will add a transport rule to PennO365 that will affect the delivery of certain messages.  This transport rule will move any message that has been filtered by our message sanitation vendor and marked as spam into the Junk folder. 

As a result of this change, email marked as spam that has previous appeared in a user’s inbox will only be seen if the user views their Junk folder.  Users should be cautioned that it is possible for email to be falsely identified as junk.  ISC recommends that users proactively use the Safe Sender Lists to ensure that email from important senders or lists are always delivered to their inbox and periodically check Junk folders for false identified messages.

If you have any questions or concerns regarding this upcoming change, please contact ISC Client Care at


ISC continues to use Message Labs as our message sanitation vendor. All mail destined for any domain that is managed by ISC is first delivered to Message Labs and scanned.  If a message is deemed to be spam, Message Labs adds a spam statement in the message header and then delivers the message to the destination email server.  It is then up to the destination email server to decide what to do with the flagged message.  ISC's legacy email services were configured to move these flagged messages directly into the Junk folder.  ISC previously decided to rely on PennO365's native spam management and opted to ignore the Message Lab spam flag for PennO365 mail.

In response to user demand we are introducing this transport rule to try to replicate the spam management behavior of our legacy email services, moving messages that have been marked as spam by Message Labs into the Junk folder.

This transport rule should affect only those messages that are being sent to domains managed by ISC.  Messages sent to,,,, and should not be affected.


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