Rather than adding lots of photos to an email message you are about to send to a Gaggle group, why not send a link to an online album instead? This has a number of advantages:
the emails are smaller, and will not use so much space in people's inbox, and will not use up the recipients' data allowance (which could be costly, especially if they are abroad!)
You will not be 'using up' the daily allowance for attachment size, if the Gaggle group is on the free plan.
If you are selling a number of items, you can remove from the album the pictures of items that have been sold, leaving only the pictures of available items.
You can also add photos to the album later, if you want - so if you take an extra picture of an item for sale, by adding it to the album, all in the group can see it.
But how do you set up such an album? On an Android phone or tablet, it's fairly straightforward. First, take your photos! Then...
This will allow you to see the photos you have taken recently - or if you want to share photos you have previously downloaded onto your device, you can navigate to the relevant folder.
Here I have navigated to a folder of screenshots, showing various walks I have taken with the local walking group, Pathfinders.
Here, I chose one of the pictures I wanted to share, and long-pressed it to mark it as selected. I then clicked on other pictures to add then to the selection (and can click again to remove the checkmark, if I've chosen one by accident). Having made my choices, I clicked on the 'share' icon (circled).
I wanted to have an album I could share via a link, so I hit the 'Create link' button, bottom left of the image on the left...
The app now uploads the images, showing a progress bar.
By clicking on the 'copy' icon (two overlapping rectangles, seen in the bottom right corner in the image to the left), I can copy the link to the clipboard.
I then used the Gmail app to compose the email to Touchbase. When I pressed and held on the screen, I was offered the option to paste the link into the email.
To summarise, use the Photos app to select the pictures to upload, click on the share icon and then the 'create link' button to upload those photos to a shareable album, then copy the link into the clipboard. Now compose the email, and paste the link into it. Recipients can then click on the link to see your album, if they want to do so.