Mail attachments not downloading (shows download arrow icon only)

I had this problem, really annoying, the attachment just sits there saying downloading instead of showing the progress. I quit mail, relaunched it, then it downloaded.

I am assuming IMAP, if so, confirm you have enabled:

In mail, Preferences > Accounts > Advanced > "All Messages and Attachments" under Keep Copies of Messages for Offline viewing.

When you hover over the message attachment, you can see the following, correct?

Alternatively you can just go to File > Save attachments, when viewing a message with attachments in Mail.

By default, attachments are saved to your ~/Downloads folder

Just change the default location to save your attachments too if you have trouble finding this folder.

Save them to a folder on your desktop if you like.

In mail preferences > General > Downloads Folder: > Choose "Other..." > Select destination folder of your choice.

incoming messages appearing in Activity but not appearing in any mail box This is normal.

emails remaining marked unread in a smart mailbox depite having been read in the Inbox. Normal as well, very annoying, I haven't bothered to figure out if there is a way to troubleshoot it. It may have to do with the server side options as well depending on your client. In particular, I get annoyed by "flagged" messages showing up with unread icons.

Please follow these directions to delete the Mail "sandbox" folder.

Back up all data.

Triple-click the line below to select it:

~/Library/Containers/com.apple.mail

Right-click or control-click the highlighted line and select

Services ▹ Reveal

from the contextual menu.* A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder — not just its contents — to the Desktop. Leave the Finder window open for now.

Quit and relaunch Mail, and test. If the problem is resolved, you may have to recreate some of your Mail settings. You can then delete the folder you moved and close the Finder window. If you still have the problem, quit Mail again and put the folder back where it was, overwriting the one that may have been created in its place. Post your results.

Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.

*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). In the Finder, select

Go ▹ Go to Folder...

from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.

Same issue!