You can prevent Mozilla Thunderbird from keeping local copies of large messages in an IMAP account. You can also prevent these messages from being downloaded for POP accounts.
How to Send Email Attachments Up to 10GB (10240MB) in Mozilla Thunderbird for Free Using Add-ons
You have so many friends. That some of them are special and others have strange habits is to be expected.
So of course you have a friend or two who sends you huge attachments in your email, like entire movies and piles of photos. Do you hate waiting for these things to download, only to have them end up in the trash anyway (unseen, mind you; just because you love the people in your life doesn’t mean you have to love—or watch—the videos they make, right?)
Mozilla Thunderbird, Netscape or Mozilla SeaMonkey can help!