Our ADA consultant advised that we add external link icons throughout our site to make it easier to navigate for people with disabilities. This seemed a daunting task until we found WP External links! This plugin has many more features we will probably use eventually, but ADA accessibility was our main goal. Initially, we had a bit of trouble getting the plugin to work out of the box, but it turned out to be an issue with the Nano3 theme that we were able to reconcile. A tip if you use anchor links - the current version of the plugin needs the full URL or it counts the anchor link as an external link. Support was speedy in helping us figure this out. I would recommend this plugin to anyone looking to retrofit their site to be ADA-friendly and automate the process of labeling external going forward.