I often send customers emails that contain one or more website links. When I do this, I always check each and every link and make sure that it actually goes to the expected location.
You don't want to send a customer an email that says "here's a link to my website" and then have them click through only to find that the link doesn't go to the correct place do you?
Website addresses have to be spelled correctly or they won't work. Best case scenario when an address is mispelled is a search engine result that may or may not contain the correct link. Worst case scenario is a "404 file not found" or "oops" page.
This is especially important when dealing with pages within a website i.e. not the home page. These page addresses can often get a bit long and complicated. In these cases, I go to the page I want to link to with my internet browser and copy the address out of the address bar at the top of the screen. Then I paste it into my email. As a final check, I click on the link from the email.
This can be a bit tricky with mobile devices which often don't make the link clickable until you send the email. In this case, copying the link into your internet browser is a good way to check if it's correct.