I use gmail via imap. I get emails with attached images. In gmail I have an imap folder where the emails land, and I also have a rule in mail that copies the messages to a mail folder on my mac.
The attachments are always visible in the gmail imap folder (from mail). In the other folder (on my mac) the images are often, but not always, visible. It is as if the attachment does not get copied, or the reference to the attachment gets corrupted -- sometimes but not every time. The whole point of copying the message to my mac was to preserve the image, so this is a bit annoying.
Update 9/11/19.
I now notice that many people are complaining about this on other forums. It happens with High Sierra and Mojave that I have heard of, and usually when imap is involved. My main mail is gmail and I use mac mail to access it via imap. Sometimes, like today, I get an email with an attachment (often jpg but today it was a pdf -- sent TWICE with the same problem) and it looks like this in mac mail: (The image is of the attachment in mac mail with the word "Downloading..." under it.
Both messages that came today with the same attachment have this problem. The attachment is there but incomplete, and trying to drag it results in a clipping, and looking at it with quick look does not work. If I log into gmail then the attachment is there and complete. This looks like the same problem mentioned on a half dozen other websites.
