Search e-mail at lightspeed: using Lookout with Outlook 2007

Everybody who uses Microsoft Outlook must know that Outlook’s search functionality sucks. Yes, I know that’s a bold statement, but there’s no other way to say it. Outlook search sucks big time, period! Even Joel agrees… My mailbox is growing every day and I find it harder and harder to keep track of its contents. A search through my archived folders often takes a much as a full minute of searching, which I find unacceptable. In the press I often read Microsoft Corporation finds Search important and lately we’ve seen them release some impressive search products (i.e. Search Server 2008 and Search Server 2008 Express). Also a major part of my daily job involves implementing SharePoint 2007 solutions at our customers, which most of the time also includes SharePoint’s search feature. But somehow the Outlook team seems to have missed the boat…

Some years ago a guy called Mike Belshe created a great free Outlook add-in called Lookout, that offered a lightning fast search. Within seconds of starting a search (often even within a second!) the results would appear on screen. Microsoft was quick to buy his company and its technology. At that time many people expected Microsoft to integrate Lookout into Outlook, but unfortunately they seem to have shelved it (Mike himself claims some of his Lookout code ended up in Windows Desktop Search). So now there’s no official way to obtain Lookout. Luckily there are many sites that still offer the Lookout download. A quick search on Google should point you to some sites containing working download links.

However, getting Lookout to work with Outlook 2007 is more problematic. It turns out that Lookout checks for specific Office Primary Interop Assemblies (PIAs) and the PIAs that come with Outlook 2007 don’t pass this test. The result is that Lookout prevents itself from running under Outlook 2007 and instead displays this warning message:

Lookout error message

After much demand Mike Belshe published a way to get Lookout to work with Outlook 2007. For this you have to rename an Office PIA file, which resides in the Global Assembly Cache. While this solution gets Lookout to work, it may have serious impact on other applications/add-ins that make use of this PIA. So this solution isn’t acceptable for me (and it shouldn’t be for you!).

Instead I opted for a different approach. The only reason that Lookout doesn’t run on Outlook 2007 is that dreaded PIA check. So why not remove it? Which is exactly what I did…

A quick Reflector session revealed that the code that performs the PIA check is located inside the assembly named Inventures_Olk.dll and goes by the name of CheckOutlookInterop(). What it does is compare the installed Office PIA’s name to a built-in string constant. If the match is positive it returns the boolean value true, otherwise it returns false. Using ILDASM I decompiled the assembly to CIL, changed CheckOutlookInterop()‘s code to always return true and recompiled the assembly. So that gave me a fully working Lookout version that’s compatible with Outlook 2007!

You can download the patched assembly here. Just replace the the original Inventures_Olk.dll with the patched version and you should be searching your Outlook 2007 content a lightspeed in no time…

Oh yeah, there’s one small issue… It seems Lookout crashes while indexing if you run it on Vista. Bummer…

Update: Recently I discovered there’s another bug in Lookout that causes dates to be parsed incorrectly if you have the .NET Framework 2.0 installed. You can read more about it here. Fortunately someone has fixed this problem and also released a patched DLL that you can download.

Update 2: The DLL I patched and offer on this blog should work with Lookout version But as I understand that version of Lookout crashes during indexing on Vista and Windows 7. In the comments below user Stroth claims he got my patched DLL working with an older version of Lookout, a version that also works with Vista and Windows 7 and doesn’t crash. That’s good news, however I never tested that.

Posted on January 22, 2008, in microsoft, search and tagged , , , , , . Bookmark the permalink. 166 Comments.

  1. I have sad news for all WIN7-Office 2010 users.
    The solution I posted on June 8, 2011 is short lived. I tried the same install on an identical machine and got an indexing error. Now the first machine it was running on, has also developed the same indexing error.

    I sent the log data to Mike and he said that Microsoft has finally succeeded in breaking Lookout forever, (at least in its current form) Any fix would be too complex and require a complete update of the code to current technology.

    Farewell Lookout. 😦

  2. Hi, try to install on win7 and Office10. Tryed all options but the OutlookAddInShim.connect is inactive.
    Does anyone have an idea how to solve this?

  3. Windows 7 Enterprise (64bit)
    Outlook 2010 Professional Plus (32bit)

    Similar instructions to Eric:
    After Outlook installation:
    1) Installed lookout 1.3.0
    2) Replaced Inventures_olk.dll in the Lookout install folder (using download link above)
    3) started outlook.

    Inexing kept crashing (Outlook would restart itself). To get indexing working go into Lookout options and:
    1) in the Index tab, uncheck Automatically Update my Indexes (not sure if required)
    2) in Advanced tab, change the Indexer Aggressiveness to the absolute minimum
    3) in the Index tab, select ONLY 1 folder that has very little or no content (if need be create a new folder in a PST file and use that)
    4) click OK
    5) click the Indexer and click start.
    6) after successful indexing, you can try increasing the aggressor and adding additional folders (you may have to try several combinations).

    I now have 3 PST files (over 2.5GB total) and the Exchange folder being indexed at full aggressiveness with no issues

    corporate IT forced the upgrade to Outlook 2007 and I thought Lookout was gone forever. Happily this DLL replacement keeps Lookout working … until the next forced upgrade. 😉

  5. Cyclops,

    I tried to install 1.3 (but not shure if is the version 24057, how can I check this?) but I have still the problem that the Lookout.AddInShim.connect is still inactive. I forgot to say that I have the 64bit version of W7.

  6. same as Cyclops
    Windows 7 Enterprise (64bit)
    Outlook 2010 Professional Plus (32bit)

    After following the above steps, the Lookout worked for a while. But two or three days later, it started to crash no matter how less aggressive it was.
    haven’t seen any reliable solution for Outlook 2010.
    what are you guys using for outlook 2010?

    • Prashant Soni

      Did you find the fix? I read that replacing only the Inventures_old.dll (not lookout.dll) worked for some. Running Outlook 2010 as administrator may also affect Lookout but never tried it.

  7. Thanx for the fix, replacing the patched inventure.dll and lookout.dll and creating text file in Lookout folder worked for me in Win7x32 Outlook 2007. Great work, thanx again

  8. Here you can find the DLL’s mentioned in the article. They aren’t available in their original location:

    • Thanx for the fix, but the link to download the DDL is no longer available. Is there any other location to download it? Regards.

      • The Dropbox link to the patched Inventures_Olk.dll should still work. It doesn’t for you?

  9. Yes indeed, it was probably a problem with my proxy, I got the file with my smartphone.
    Thanx for your quick answer.

  10. As it was already depict the Outlook search functionality was good but not perfect. If you want to operate easy and fast you should try lookeen. This add-on is maybe the successor of looktout. More information on
    Best regards, StefanS
    Disclaimer: I work for Axonic – Vendor of Lookeen.

  11. This is an old thread but I thought I would update it with new information for Outlook 2013 on Windows 7. Lookout will still work under Outlook 2013 and windows 7!!

    The process is basically the same

    1.) Download Lookout 1.2 –
    2.) Download Inventures_Olk.dll –
    3.) Download Lookout.dll –
    4.) Close Outlook
    5.) Install Lookout 1.2
    6.) Copy Inventures_Olk.dll and Lookout.dll to the lookout installation folder and replace the existing files.
    7.) Open Outlook – If the lookout setup process runs then you are complete. If not continue to the next step.
    8.) Select File -> Options -> Add-ins
    9.) Next to Manage COM Addins, select GO
    10.) Check the box for Lookout and select OK.
    11.) It should load lookout and you can find the search bar under the ADD-INS tab.

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