in the standard email client I do not see attachments, how do I see them?
Double click on the email so that the preview/viewing pane opens up and then they're just below that.
I made you a helpful graphic:
You can double-click on the attachment and open it in the default client. If you right click on it, your choices are 'open' and 'save'.
After a few tests, they all showed up. If you're unable to see an expected attachment, I'd suspect that it's a malformed email. I was able to send and receive several emails with attachments in short order.
Tested with eOS Here 5.1.7