Update 2nd May 2018:

Microsoft have just released the LAA patch for the issues below, KB4018376 for Outlook 2013, and KB4018372 for Outlook 2016. It seems to work, as I can see a lot more memory available for Outlook 2016 after this patch, and will update later once I can confirm the below issues are resolved.

Original Blogpost:

Since going from Outlook 2010 to 2016, I’ve noticed several issues. They’re outlined on this TechNet article which lists:

• Buttons on the Outlook ribbon failing to paint properly
• Email messages displaying either blank or black in the Reading Pane
• The Navigation Pane failing to draw all folders properly
• Various rectangles appearing in the Outlook user interface (UI)

There’s also just Outlook crashing/freezing/running slow. This has been an ongoing problem, and I suspected 3rd party addins to be the culprits. That’s sort of true, however it turns out it’s an overall memory issue with 32 bit Outlook having ~2GB of RAM to access, shared amongst all the 32 bit apps running on your computer.

If you want to know that low memory is the cause of your issues, one way is to use the Sysinternals VMMap utility and follow these instructions. If your free memory is under 250MB, then you’re working below the requirements of what Outlook needs to have available to continue running smoothly.

The article above is very well written and detailed, with the primary remediation suggestion being to go 64 bit Office. This isn’t a short term realistic solution for many companies who have legacy 32 bit addons, or vendors who just haven’t got there with 64 bit addins yet. It only takes 1 addin for that idea to come crashing down, and then there’s the testing of all the re-written apps, and then deploying out; an uninstall of the whole Office 2013 or 2016 32 bit suite, uninstalling all the addins, deploying Office 64 bit, deploying the new addins… it’s potentially a huge project to take on.

There is hope though for those of us who can’t go 64 bit (again the article has many suggestions), which is a new feature called Large Address Aware (LAA). It doubles the amount of memory (4GB) available to the Office apps. It’s already rolled out to Outlook 2016 build 1709. That makes sense if you’re using the Click to Run (CTR) version of Office 2016, but the MSI version that many still use hasn’t got this update yet. Referring to the TechNet article again on this issue, there’s no exact specific mention that LAA will come to the Click to Run version of Outlook 2016, so we’ll have to wait and see.

If you’re experiencing a less than great experience with Outlook 2013 or 2016, it’s worth understanding the above and seeing if you’re affected. This may drive you to change to Office 2016 CTR, Office 2016 64 bit, or even both – or leave you to work out how you can improve the experience, with potentially disabling Outlook addins that aren’t necessary.

I am trying to work with Microsoft on this issue too, so feel free to ask any questions or make any comments and I’ll see if I can assist.