Outlook antivirus exclusions (reminder)


Hi all,


Here are a few examples of which issues you can expect as well if some software are preventing access, even temporarily, to Outlook Cache mode files:

- a manager with many secretaries who have delegations rights on this manager’s mailbox, and who organize meetings on behalf of the boss – inconsistencies will arise overtime on meeting organizer and meeting attendees, which can be directly related to AV scanning Outlook cache files (OST, OST.tmp,xml,…) – or any other software who can have a handle on these files.

- desktop load from other application also plays a role in the frequency the above mentioned issues appearance, as applications like Outlook may be slower to process elements and will need more time handling OST, ost.tmp, profile_name.xml, .oab, etc… files and need more constant access to these => if the antivirus are handling these files at the same time, chances to have issues are multiplied.

- Outlook in cache mode is freezing as the application is trying to access its OST or other cache related files (as well as PST files sometimes “hooked” by AV software – remember not to put PST files on network shares or mapped drives) – Outlook in cache mode will NEVER freeze, unless the mentionned case on this example, OR any piece of online mode that is used on the user profile (Example: access to shared folders or mailboxes for which cache mode is not configured – this is a check box on the Outlook options for the current profile, or the OAB is not downloaded, then Outlook uses Online mode Address Book for example)

Note that frequency of these also increases as certain conditions of daily utilizations are met.The above examples of issues can be hard to reproduce on a lab.

I’m adding some more information regarding Outlook latency causes that can be on the Desktop side.


> Outlook 2007/2010 – More precisions about Antivirus exclusions and things that can slow down your messaging client in general




> Plan antivirus scanning for Outlook 2010



- We recommend that you turn off scanning of the following Microsoft Outlook files:

  • *.oab (Outlook address book files)

    %userprofile%AppDataLocalMicrosoftOutlookOffline Address Books<guid>

  • *.srs (send/receive settings files)


  • Navigation pane settings file profile_name.xml files

    %userprofile%AppDataRoamingMicrosoftOutlook<profile name>.xml

    where <profile name> is the name of the Outlook messaging profile, as shown in the Control Panel, Mail applet.

  • outlprnt (print styles)


-  If you use antivirus software to perform file-level scanning [Outlook files], while Outlook is in use, data corruption issues might result.

- We we do not recommend that you scan *.pst, *.ost, and other Outlook files directly. Instead, we recommend that you scan email message attachments on the email server and on the Outlook client computer.


> How to troubleshoot performance issues in Outlook 2010



- The performance issues may be caused by one or more of the following: 

  • Insufficient computer specifications
  • Absence of the latest service pack for Outlook 2010
  • Large Personal Folders files (.pst) or Offline Folder files (.ost)
  • Outlook .ost files or .pst files that are stored on a drive with insufficient write performance
  • Third-party add-ins
  • Gadgets that access Outlook data (Windows Vista only)
  • Microsoft Office Communicator integration
  • Antivirus software interaction
  • Windows Desktop Search indexing
  • Incomplete closure of .pst files or .ost files
  • POP3 accounts on Windows Vista clients
  • Many Really Simple Syndication (RSS) feeds
  • To-Do Bar and Online mode with Exchange server
  • Damaged Outlook messaging profile

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