Create a column in your sheet/CSV (with all the unique image links for all your leads).

Host your image on something like Google Photos (upload it there and use the share link) to get a perfectly trustable image host. Click on Share, and then Create link.

Copy the shared link of the image from the Google photos.

When you get the share link from Google Photos, paste it on this website to get an embed link that you can finally use in Instantly.

Paste it under Google Photos, then copy the Direct Image link.

Now Insert the direct link in your CSV file.

Set the column name to "ImageURL" (ensure that there are no spaces in between the variable name, otherwise it won't work) and then import it as a custom variable to Instantly.

Once you've done that, you can just go to your sequence editor and add a random single image from the ones you have the way you would normally add an image (just so the HTML code for the image shows up).

Go to the Code View -> find the code for your image and then change the src="url" (the whole url as shown below) to src="{{ImageURL}}"

Original Link:

Change the original link to a variable {{ImageURL}} but make sure you keep the "".

Once you've done this, click out of the code view and even though the image might appear broken in the sequence editor - you will be able to see it working in the preview mode.

Click Preview to preview the image or send a test email to double-check that the image works.