Thunderbird ices up when downloading and install huge mails

Going grey does not nessesarily suggest that TB collapsed with a freeze. It signifies you that the application is active. Just being active for a countless time would certainly be a freeze. If your application proceeds pursuing the download ended up IMO every little thing is simply great.

Failing to read currently downloaded and install mails while a bigger download runs is extra like a wishlist attribute for TB. Yet consider this : when having actually set up your account with IMAP you might not have the ability to add a more download when the program still is active downloading and install.