I've recently added my iCloud account to Thunderbird, and can use this along with my other accounts, yahoo, gmail and so forth. icloud.com, however, has a useful feature, which is that if you try to send an oversized attachment - anything up to 5Gb - it will automatically send it via Apple's Mail Drop facility: that is, it will store the attachment for 30 days and incliude with your email a link from which to download it. This also works with Apple's Mail app, but it doesn't work with Thunderbird; with Thunderbird I just get the familiar 'attachment too large' warning, and the email is not sent. My question is twofold: first of all, should it work? i.e. is there something I haven't done properly in setting the icloud account up; secondly, if it's technically not possible for it work, why is that? I don't understand the mechanisms of internet connection to know why this might be. Thanks in advance to any experts on this topic!