Why does Outlook launch IE in the background?

I have been noticing erratic behavior with Outlook 365 for some time and when trying to end tasks have noticed Internet Explorer running (which I never use). After some testing it seems to be the exact same issue that so many people have been reporting here for almost TWO years.

While searching, I found this recent article from Microsoft: https://techcommunity.microsoft.com/t5/Windows-IT-Pro-Blog/The-perils-of-using-Internet-Explorer-as-your-default-browser/ba-p/331732

WHY is Outlook launching IE if it's so perilous to use?!

I have the latest Windows 10 Pro and the latest Office 365 and am an admin.

Hello,

I have been experiencing this same issue on a users machine (Windows 10 1809, Office 2016 pro plus x64) seeing that two IE windows were launched in the background of Outlook causing it to crash on startup. I did notice however that after Outlook had run for some time the two IE windows would close and the stability of the machine would return to normal. 

After going through multiple troubleshooting setups, upgrading the user to O365 ProPlus and trying various suggestions found in the post. I found that the user was running Microsoft Dynamics 365 plugin (version 8.20002.0137) I disabled the plugin as a last-ditch effort to resolve the issue and found that the IE windows no longer appear and Outlook runs without crashing.

I can only imagine that these windows appear so that the plugin can connect to our CRM database to pull down any updates or changes that have been made since the user last connected. I am not sure if this will resolve the problem for other people in this forum but it might help some.

Sadly in our case, this now means our user is unable to use this version of the Dynamics plugin but I will be testing other versions soon to see if we have the same result.

Please note that in our case we are running a hybrid 365/On-prem environment with the majority being hosted in 365.

Regards

Sam Perry

@Microsoft

Any chance we can get this fixed anytime soon as it has been ongoing since May 2017 and still iexplorer.exe is loading on opening Outlook.

I am running on O365 2016 release: 1811 (Build 11029.20079 Click-to-Run)

Outlook for O365 MSO Version:  16.0.11029.20045 32bit

On RDS we push everyone over to Chrome but iexplore.exe is still loading as everyone uses Outlook which is wasting system resources.

We just checked in a fix to build 16.0.11005.37379, so any Insider Fast build higher than that should have the fix.

I just checked on the integration status. Integration happened in build 16.0.11012.10000. So that's the build to really watch for.

We have also noticed this behavior and are testing with the Monthly-Targeted channel (build: 16.0.11029.20045).  We have IE Protected Mode turned on for Internet Zone and Restricted zone, but off for Intranet and Trusted Sites.  We have tested turning it on for trusted sites and Intranet zones but are still experiencing the same symptoms (When launching Outlook in Safe Mode or otherwise, 3 IE processes are launched.  When closing Outlook 2 IE processes remain).  I have also verified the registry key (HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\ProtocolDefaults\osf-roaming.16=3)

Are there other Office or Internet Explorer settings that could interfere with the implemented fix?

If it is helpful, I can open a premier case so we can do some screen sharing as well.

Thanks!

Thanks for all your help, Stephen.  Nothing on the Win10 machine is old.  Outlook has an "Exchange" COM add-in (UmOutlookAddin.dll).  I connect to exchange.  I have the 32-bit version now (recommended by the store) but would prefer 64-bit.   ???