BrowserShots (free and used to be my favorite, although the slowness made alternatives more attractive).The upside however is that most of these allow easy summarizing of screenshots so you don't have to start session after another and get screenshots. The downside is that you can't interact with it. But contrary to the previous, don't grant interactive access to the actual machines but only to get screenshots. If you don't need interactivity and or need a cheaper solution (note that this method may not always be cheaper, do a little research before making assumptions) there are also services online that, like the previous one, have access to real browser/OS environments. Sometimes causing errors that don't occur in the real browser, and maybe not having bugs that the real browser would have. The downside is that these emulations are often less stable than the real client, and are even harder to debug with because they don't run in the natural environment of the browser.
In the past, there were also native Mac applications (such as ies4osx), or as a Windows application which requires a VM if you don't have Windows (such as IETester or MultipleIEs). Internet Explorer for Mac the Easy Way, 2011-09,.
Check one of these articles to get that up and running:
Microsoft offers free VM images of simplified Windows installations for the purposes of testing Internet Explorer and Microsoft Edge ( download). You may or may not know this, but you do not need to get an official copy of Microsoft Windows for these virtual machines. You can use VirtualBox (free and open-source, similar to VMWare or Parallels) to create one or more virtual machines on your computer. There is also CrossBrowserTesting, browserling/ testling, which seem to have similar services although I haven't used these myself. Both of these also support setting up a tunnel to/from your own machine so any local hostnames will work fine. You'll be able to pick a browser of choice, enter a url and use a real OS with the real browser and test and interact as much as you need. Use something like SauceLabs or BrowserStack. There's three different methods that I recommend:
Download some virtual machine software.The instructions below include free and legal virtualisation software and Windows disk images. You will need one virtual machine for each version of IE you want to test against. On an Intel based Mac you can run Windows within a virtual machine. Update: Microsoft now provide virtual machine images for various versions of IE that are ready to use on all of the major OS X virtualisation platforms ( VirtualBox, VMWare Fusion, and Parallels).