After enabling the Blank Subject and Sender rule and enabling the rule for "Internal Messages (Store)" in Symantec Mail Security for Microsoft Exchange (SMSMSE) certain contacts and out of office templates are deleted when a scan is run on the mailbox or folder containing the contacts file or out of office template.
When an out of office or contacts file is created in Exchange, an email message is inserted into the Exchange database with no subject line and no sender line. This causes the "Blank Subject and Sender" rule to fire as configured.
Apply the Blank Subject and Sender rule only to "Inbound" messages. This is the default configuration for the rule, but if the rule has been changed to also scan "Internal messages (store)" these system generated templates can also be affected. Symantec recommends leaving this rule at the default configuration of applying only to "Inbound" messages: