Remote resources have been blocked, mail

error:
To protect your privacy remote resources have been blocked. (images are blocked)

at Gmail also

error: show a picture…

That behavior is for security reasons. I could send you a file that could hijack your outlook or web browser in the case of roundcube.

If you want to see the images click on “see pictures”.

If you want your pictures to be displayed when you send an email, then you have to code the images into the email itself.

can i stop it

You need to check Roundcube docs.