Why does Outlook launch IE in the background?

TL;dr

Outlook starts two IE processes that shutdown when Outlook does: This is normal

These two processes don't shutdown: This is a bug, under investigation

These two processes are a huge perf problem: This is not normal.

Hey - Outlook Escalation Engineer (read: debugger) here. I just wanted to add some clarity:

Outlook (all of Office really) uses Internet Explorer to handle Office Add-Ins, as suggested earlier in the thread. Originally, we would launch IE right when we needed it to handle an add-in, but we found that sometimes IE could take a while to load. So we made a change: now we "preheat" the add-in architecture when we launch Outlook. We go ahead and launch IE to get it ready for when we need it.

This is why it doesn't matter if you're actually using any add-ins - we can't know that in advance, so we still warm up IE. And this is why IE will come back after you kill it - if you do an action that would activate an add-in you do have (like opening a message), we will launch IE.

This is also why those of you who have chosen to uninstall IE now find that add-ins don't work. You removed a component they depend on.

The design of IE also dictates that it uses a different process for every site opened, along with a master process for the user interface. This is why, if you have several tabs open, you'll see several IEs in task manager. So when Outlook launches IE, IE will in turn launch another instance, leading to the two you see in task manager.

The design for Office's use of IE for add-ins also dictates that IE is shut down when the Office application is shut down. I do understand that there is a scenario where this does not happen, and I'm investigating it.

Here's the problem - the APIs we use to talk to IE do not like it when Protected mode is disabled:

https://support.microsoft.com/en-us/help/2761180/apps-for-office-don-t-start-if-you-disable-protected-mode-for-the-rest

https://blogs.msdn.microsoft.com/deva/2017/11/01/understand-more-about-office-js-its-add-in-runtime-environment-and-internet-explorer-protected-mode/

The scenario I'm investigating involves just that: Protected mode is disabled, Outlook launches IE, but IE does not shut down when Outlook does. That definitely sounds like a bug (though I'm not sure yet if it's on the Outlook/Office or IE side). I've got a repro here and am debugging it right now. So if your issue is that you get more and more IE processes as you start and stop Outlook, I hope to get to the bottom of that soon.

Finally: For those of you reporting that two IE processes are enough to tank the performance of your machine. I'm afraid you may have bigger problems going on. Outlook hasn't actually asked IE to do anything - just to be running so it *can* ask it for stuff later. I would take a close look at any Internet Explorer add-ons you have have installed. I would also be very concerned about possible malware. This thread does seem to highlight some Windows version related issues:

https://social.technet.microsoft.com/Forums/office/en-US/de34e4b2-0c48-4486-ab75-0a54136748d1/outlook-2016-crashing-internet-explorer?forum=Office2016setupdeploy

We are using Exchange Online.  

If Outlook is run as an administrator, iexplore.exe still opens in the background but does not crash.  Running Outlook as an administrator is not a solution, however.  Our users do not have local admin rights on their systems, so they cannot run Outlook as an administrator.  We cannot enter admin credentials every time that someone needs to open Outlook.

I can see that iexplore.exe runs in the background by checking Task Manager.  I open Task Manager and verify that neither Outlook.exe nor iexplore.exe are running.  I open Outlook and watch Task Manager, and I see two instances of iexplore.exe start while Outlook is opening.  IE windows never appear in the GUI.  When Outlook closes, the two iexplore.exe processes close, too.

We have seen Outlook launching iexplore.exe on several systems.  It probably happens on every system that has the latest Office updates.  The iexplore.exe processes are crashing on one system currently.

Evan

Another in a long, long,  line of examples of Microsoft  incompetence/dishonesty/deception/general lack of respect.   Pick one or all.  We are currently looking at moving to Apple or Linux.  Tired of wasting time and money with MS.

Hey Evan,

I also noticed this issue when running CCleaner and it had to "close IE processes" when none were actively open.

I uninstalled IE by going to Programs and Features, clicking Turn Windows features on or off, and clearing the Internet Explorer 11 check box.

After doing this the Outlook "Action Items" tool stopped working (see below).

Based off of my observations the Internet Explorer process is being used for the "Action Items" tool in Outlook, which is intended to scan through an email and highlight possible action items. I suspect it is done for the same reason Apple's Siri uses remote servers for processing.

Hopefully this helps at least point to why the process is appearing.

Cheers,

-Jordan

Thanks, Jordan.  This is the best explanation that I have seen so far.

Hey Evan,

I also noticed this issue when running CCleaner and it had to "close IE processes" when none were actively open.

I uninstalled IE by going to Programs and Features, clicking Turn Windows features on or off, and clearing the Internet Explorer 11 check box.

After doing this the Outlook "Action Items" tool stopped working (see below).

Based off of my observations the Internet Explorer process is being used for the "Action Items" tool in Outlook, which is intended to scan through an email and highlight possible action items. I suspect it is done for the same reason Apple's Siri uses remote servers for processing.

Hopefully this helps at least point to why the process is appearing.

Cheers,

-Jordan