Although this is technically a blog, it's primary content is a series of articles on how to get Firefox working in a corporate Windows environment. Later ones build on earlier ones, so you might want to use the Table of Contents on the right to read through it chronologically instead of reading straight down from here.

Dealing With Those Pesky IE-Only Sites (IE Tab v2)

Last updated September 2017
(This is instructions for using IE Tab v2.  For IE Tab Plus and IE View, go here.)

Sadly, even in this day in age there are still a few IE-only sites I have to deal with.  However, we can use the IE Tab v2 extension to manage this problem.  It uses Internet Explorer to render pages in a tab that looks like any other Firefox tab.  It's transparent to the end user.  You just need to specify which sites it should be done for via my login script.

Important: These instructions require you to use the Firefox 52 ESR releases and also add this line to the login script:
"plugin.load_flash_only", false
This is because non-Flash plugins, which IE Tab uses to function, are no longer supported in the regular Firefox releases.  Also, all extensions not written in the newer WebExtension format will no longer work in Firefox 57 and later.  Firefox 52 ESR will get security updates until May 2018 so it's safe to use it until then.  If no WebExtension version of IE Tab is released by then, oh well.  For more information see The Death of Plugins.

Configuring IE Tab v2

You should add these lines to firefoxSettings in the login script:
var firefoxSettings = new Array(
   "extensions.ietab2.filter", true,
   "extensions.ietab2.compatMode", "ie8mode",
   "extensions.ietab2.hasRun", true
The first setting makes sure it's enabled.  The second setting tells it to render pages in IE8 Standards Mode, since it uses IE7 by default and there's no reason you should be using that.  There's also an IE9 mode if you have that installed, but 8 is the highest version available for Windows XP.  The third setting helps prevent it from opening a welcome tab the first time it's used, but it also requires an edit to be effective.

When you first use this extension it will pop up a changelog, which I think would be annoying and/or confusing for end users.  If that's not a huge deal for you you can package this extension as a MSI without any edits and push it out.  If you want to go the extra mile you can remove the line of code that does that, but it requires getting the edited extension signed before it can be used on Firefox 48 and later.

If you're willing to do that, edit chrome\content\ietabOverlay.js and find and delete this line:
Then follow the rest of the instructions here to get it signed before packaging it into a MSI.

In the login script there's a variable called ieTabRules which is where you put the regular expressions that determine which sites get opened in an IE tab.  Add entries like below.  Because they're regular expressions you have to include asterisks at the end.
var ieTabRules = new Array(
If you want to configure any other settings go to about:config in your browser, look at what's available under extensions.ietab2, and add what you want to firefoxSettings.


  1. This blog has been an excellent source of information for getting Firefox deployed across our organisation, especially with Mozilla's reluctance to create official MSI packages. This page in particular, was great for getting IE Tab both installed and configured automatically. Unfortunately as of FF 56 it's stopped working and appears to have been abandoned, and I can't find a suitable alternative :-(

    Many thanks for the excellent blog posts over the years though! If anyone finds an updated version of IE Tab that does work, please comment below! :)

  2. Yup, I haven't been able to either. I switched my organization to the ESR release which still supports everything to buy some time, but eventually I'm going to have to give that up. If there's no WebExtensions version of IETab (or XMarks for that matter) I'm just going to have to abandon them. People will have to sign up for their own Firefox accounts if they want their bookmarks to sync and they'll have to open certain sites in IE manually. IETab does have a Chrome version so I don't know why that code can't be adapted.

    The last Firefox 52 ESR release will be in May 2018, so that's how much time is left, assuming I don't want to move earlier to get Quantum and to switch to 64-bit. I've already had some people's Firefox slow to a crawl when they hit the 2GB memory limit of the 32-bit version.

  3. I updated the site and several of the individual pages with information on this.

  4. I've been on the standard release, simply because users want new features and they'll just use Edge/IE if Firefox doesn't get updated to provide them. With the death of IE Tab and no WebExtension alternative that I can find, I may look into going towards the 64-bit version, and the upcoming Quantum as well of course. Most of our remaining IE only sites are so old that it's becoming more of a struggle to get them to work at all, let alone in Firefox, so this isn't as bad for my organisation as it will be for others who are more dependant on IE Tab.

    Your user.js post has been a lifesaver for us though!