|Please do not double post - it makes it fiddling to repeat everything.|
My guess is that they are actually big but when you view them normally your viewer reduces them to fit the page.
By whatever means they have to be downsized for email. One way is to use the E-mail button at the top of "Windows photo gallery" when you are viewing them.
There are various ways to create downsized copies with photo programs too.
Your email client might have a downsize facility but that would depend on what email you are using (not given).
Here are some other ideas about downsizing for email in bulk:
Always pop back and let us know the outcome - thanks