I couldn't download any attachment from Gmail for the last couple of days. The problem might be with my ISP or my router's MTU who knows. So I tried to download the attachments embedded in the RAW email.
First I opened the RAW email from any mail's "Show Original" menu. Then a page with the attachments appeared encoded in base64 encoding. This page may be huge in size as all your attachments are embedded there. Save the page as
Download mpack package using apt or rpm or pacman.
sudo apt-get -y install mpack
This is what I used on my Kubuntu system. Then I navigated to the directory I saved the email.txt file and fired up the munpack command.
minhaz@minhaz-desktop ~/download> munpack email.txt Database.zip (application/zip) www.zip (application/zip) nginx.zip (application/zip) minhaz@minhaz-desktop ~/download>
You will then find the attachments extracted to that directory.