Instead of trying to search a tab, search engine or your Windows search bar for GMX mail login page, you can bookmark the official GMX mail login page and visit the page only when you want to log in to your GMX mail account.
The right URL on the official home page for GMX is https:/www.gmx.com. It's also the only URL to log into your GMX email account that you can use. Enter the full "www.gmx.com" URL in the address bar of your browser instead of entering phrases like "GMX mail login."
Most browsers will use phrases (which are not formatted with URLs) that you entered as search phrases on their address bar, bringing you to the search result when you press Enter. This is not the right way to visit a page you have already chosen to visit in the first place, because search engines do not always guarantee to display the genuine and correct pages you wish to visit. However, if you do not remember the URL of the page you would like to access, well, this might be the only way to check for it.
The correct way to visit the GMX mail login page is to type the full URL address - www.gmx.com - into the address bar of your browser and click Enter. Then next time you can bookmark the page for even easier access. This way, you will be assured to visit the right and valid GMX email sign in page, but not other non-relevant, fake pages or those claiming to be the official GMX attempting to steal accounts from users.