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How to run multiple, separate instances of Outlook!

Ok, ever since Outlook 2000 I’ve been looking for a way to access more than one Exchange server account using Outlook. I recently started using Outlook 2007 and I finally got fed up with not being able to access both my personal Exchange account and my work Exchange account on my home machine. I started digging for a solution… someone somewhere had to have a hack. It turns out there is one!

Normally when you launch a second instance of Outlook, that new instance first looks for an existing Outlook window. If it finds one, it passes a Windows message to the original instance, prompting it to open a new view, then the second instance terminates.

Jason Geffner of NGSSoftware and Reblog has created a solution called ExtraOutlook, which stops this from happening. You can run as many instances of Outlook your machine can support (Outlook = resource hog). All you do is create multiple Outlook profiles, then run ExtraOutlook and pass it the path to Outlook.exe and any command line options you want. For example:

C:\Utils\ExtraOutlook.exe “C:\Program Files\Microsoft Office\Office12\Outlook.exe” /profile “MyProfile”

When working on my home machine, I now use a single batch file to launch both Outlook profiles. To avoid accidentally running it twice and launching multiple instances that access the same mailbox, which could cause mailbox and PST/OST corruption issues, I included a little process check routine just in case:

@echo off
tasklist | find /I “outlook.exe” > nul
if %errorlevel%==1 (
rem — launch outlook profiles —
C:\Utils\ExtraOutlook.exe “C:\Program Files\Microsoft Office\Office12\Outlook.exe” /profile “Work”
C:\Utils\ExtraOutlook.exe “C:\Program Files\Microsoft Office\Office12\Outlook.exe” /profile “Personal”

One of the quirks appears to be the processing of things like OLE commands, linked email/MAPI functions, MailTo: links on websites, etc. From what I can tell, the last instance of Outlook to launch is the instance that handles these events, which is why my work profile launches before my personal profile. So far it’s worked that way for me, but this might just be coincidence… I’ve only been using it for a couple days now. Other software packages may integrate with Outlook differently and may yield different or undesirable results. Since I don’t use any outlandish plugins or extensions for Outlook I think I’m fairly safe.

All in all, this is friggen fantastic. I get both Outlook windows running at the same time, and even reminders and alerts for both instances work. I have no idea why Microsoft would limit Outlook to only running as a single instance, but there may be a good reason. Therefore, use this utility at your own risk. Make backups regularly!

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5 Responses to “How to run multiple, separate instances of Outlook!”

  1. Jason Geffner says:

    Thanks for the feedback 🙂

  2. Mattie Peeters says:

    @echo off
    tasklist | find /I “outlook.exe” > nul
    if %errorlevel%==1 (
    rem — launch outlook profiles —
    C:\Utils\ExtraOutlook.exe “C:\Program Files\Microsoft Office\Office12\Outlook.exe” /profile “Work”
    C:\Utils\ExtraOutlook.exe “C:\Program Files\Microsoft Office\Office12\Outlook.exe” /profile “Personal”

    Iets klopt er niet aan dit script. krijg foutmelding:
    ZOEKEN: ongeldige schakeloptie
    in windows7

  3. Mark Shipp says:

    I too have used ExtraOutlook for several years however, I just upgraded to Outlook 2013 (on the same computer) and it no longer functions. I would love to hear from someone that has figured out to make it work with Outlook2013…. or an alternative program that will let me run two instances out Outlook at the same time.

  4. Amal says:

    Hey Mark, I’m just curious – why would you want to run multiple copies of Outlook 2013? The problem with older versions was that you could not get good separation between multiple accounts unless you ran two copies, but Outlook 2013 is great at managing multiple accounts, even multiple Exchange accounts.

  5. Mark Shipp says:


    Well I am about a year late in answering your question so apologies.

    The reason I run two separate instances of Outlook is that I run 2 separate businesses and this is the most efficient way for me to manage those businesses (complete separation). I have never been fond of switching between email accounts (or having multiple accounts in the same instance) as it is inefficient and the newer versions of office are no better in this regard.

    My screen is split horizontally with my primary business instance running on top and my second business running on the bottom half of my screen. This keeps me more efficient and productive without having to switch between accounts as I can instantly see incoming email and respond. There is no scenario you can think of that will work for me with a single instance of outlook.

    I have reverted to Office 2010 as I cannot get ExtraOutlook to work on 2013+ but it does work fine with Outlook 2010.

    I am absolutely still interested in knowing if anyone has come up with a way to make the newer versions work with multiple instance running.

    Mark Shipp

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