First, please check if your links were inserted with http://.
Google Analytics can also cause issues. Please check if your links work without the GA link parameters.
If you sent a preview email and notice that the links are not functioning properly you can edit them retroactively, even if the email was already distributed.
The link contained in the email is just a tracking link. The actual URL is passed on by our system.
Open the report for the respective email and click on [Links] > [Click performance].
By clicking the  button you can change and correct the link.