Hi   !
Would you take a look at the article :
Mixed content blocking in Firefox
You'll get that warning signal when there are images on that particular page. As long as you don't mind that there is a very slight chance that somebody, who has nothing better to do, might take a look at those images :   nothing to worry about.

i do not know if was helpful because I have not tried it

JOHNTHEWALK said

i do not know if was helpful because I have not tried it

Then : will you let us know after you've tried it, please  ? (Take all the time you need  !)

I do not for instance see a padlock with a line through it on the Royal Mail's login page

• https://www.royalmail.com/user/login

If you are using the site to track mail deliveries you probably have no need to worry about the security. If on the other hand you are paying for mail services or stamps etc. then you certainly do not want to be using insecure pages in case it allows someone to eavesdrop and gain information about your banking.

I just went to :  www.royalmail.com and that's where I saw the grey padlock with the red line through it, and that's how it should be, as that page if filled with images. Absolutely normal   -   - nothing wrong with it.

I recommend using the secure login page:

John99 said

I do not for instance see a padlock with a line through it on the Royal Mail's login page

• https://www.royalmail.com/user/login

This site uses an older design: it accepts logins over a HTTPS connection, but handles regular browsing over an HTTP connection. Amazon used to work the same way. This is not ideal because it increases the risk of session hijacking and allows others in the path between you and the site to track every HTTP request and read every HTTP page you get in response. Hopefully the site will eventually switch to all-HTTPS for the whole site. Feel free to urge them to do just that!