In SMEX, when a Scheduled or Manual Scan runs, the timestamp on the email is modified. Some email backup or archiving system may be affected.
When performing Manual or Scheduled Scan, SMEX adds timestamps for the scanned items. This timestamp is necessary to confirm whether a particular message is scanned or not. As an example, if you select the option "Scan messages that have not been scanned" on Manual Scan/Scheduled Scan, SMEX will check the timestamp to confirm whether the corresponding message has been scanned or not.
This behavior of adding a timestamp affects email backup and email archive. These features work based on the message's last changed time.
- TrendMicro must add the Virus Stamp "X-MS-Exchange-Organization-AVStamp-Mailbox" after scanning a message based on Microsoft's standard.
- Read more about AV Stamp in this MSDN article.