Richard,
When you say you selected the smallest size, are you referring to the words that show up around the frame of the photo when you add it to your message? If so, that doesn't actually shrink the size of the image file; it only reduces the display size of the image. If I'm misunderstanding, you can ignore the info below. Otherwise, try resizing the files using Windows before you add them to your post.
1. On your Dell, try opening the photo in the Windows Photos app. In the upper right, click the three dots menu. If you select File Information, it will show you the dimentions and file size in MB on the left. You can see my photo below is 12.2MB, which would not work with Google Groups file size limit:
2. Select Resize from the three dots menu shown in the image above. You'll get the Resize window shown below:
3. Select M (medium) unless there is some small detail in the photo that you really want to preserve (like lug lining) - then select L (large). Both sized will look nice on a screen.
4. On my computer, a Save File dialog opens up. Just save the file somewhere and add -small to the end of the file name so you know that it's the smaller one.
5. If you go to the File>Propoerties of the new resized image, you'll see that the file size is drastically reduced:
6. But it still shows up really nicely in the message
Paul in AR