WebTechee

Smart External Links Manager detects external links in post content and adds:
<ul>
<li>target=”_blank”</li>
<li>rel=”noopener noreferrer”</li>
</ul>
Internal links, anchor links, mailto, and tel links are ignored. 
This plugin is intentionally lightweight and works out of the box without configuration.

Webtechee External Links Security

Automatically adds secure attributes to external links in post content.

XAce90

Casper’s Leave Notice warns your users when they are about to leave your website. All you have to do is install and activate, and the plugin does the rest! You can edit the content that shows up in the pop up window to fine tune the message your users see. You can also add domain names to exclude from the pop up.
For example, if a link sends your users to a third party tool – like a shopping cart – just add the domain to the exclusion list and your guests will be none the wiser.

Casper’s Leave Notice

A quick, easy way to notify your users when they are leaving your site. You can edit the content and add domain exclusions.

Webtechee External Links Security vs Casper’s Leave Notice