The very design of HTML uses both a hyperlink and link text. All you're supposed to see is the link text, but that has led to various and sundry deceptive practices. Here's how to see the actual URL in both OS X and iOS, in both mail and Safari.
1. Mail in OS X. We're all very familiar with this and have been using it for years. Hover the mouse cursor over the suspect hyperlink and a rectangle will pop up showing the actual URL.
2. Safari in OS X. If you have Safari > View > Show Status Bar enabled, you'll see a bar at the bottom of Safari that reveals the actual URL. In the link below, there's a long string of text, starting with "dark-matter..." You can see that it takes you to an article at Nature.com.
3. Mail in iOS. In iOS, you must tap and hold the link, and then you'll see a popover that contains the actual URL at the top along with some other options.
To avoid going to that link, tap somewhere else on the iOS display. The popover will disappear.
4. Safari in IOS. This works just like iOS mail in #3 above. Tap and hold the link to see the actual URL.
Using these techniques will make sure you always go where you think you'll go on the internet by providing a preview of the actual URL.
Teaser image via Shutterstock.