我上MAIL主機已刪掉一大半的舊MAIL了，而且TB內的收件匣能刪的能移開收件匣的，
全都做了(目前已把收件匣內的所有MAIL移至TEMP匣)，壓縮郵件也做了，但仍然顯示相同的警告!!!
"「收件匣」已滿，無法新增郵件。請刪除不必要的郵件後壓實重整此郵件匣"

請參考網頁「 http://forums.mozillazine.org/viewtopic.php?t=604738 」所提供的方法，
「 Post Posted December 22nd, 2007, 10:08 am
Close Thunderbird. Find and delete all of the files with the .msf file extension in your profile folder/Mail http://kb.mozillazine.org/Profile_folder_-_Thunderbird including your Local Folders, especially if you are using the global inbox. You must have "View hidden files and folders" on http://spywarewarrior.com/viewtopic.php?t=272 and you need to set "hide extensions for known file types" off (just below View Hidden) if you are using Windows. These are your mail summary files and do not hold any messages themselves. They will be rebuilt the next time you open each folder in Thunderbird. Compact all your folders when you have completed this. http://kb.mozillazine.org/Compacting_folders

To avoid this happening again, see the tips in these articles:
http://kb.mozillazine.org/Keep_it_worki ... derbird%29
http://kb.mozillazine.org/Performance_%28Thunderbird%29 」
謝謝。

我也遇到此問題,感覺是"自己懶"的關係(因為大部分信都還是直接放在"收信匣")
我的作法是
1.收信匣下新增一個"分類資料夾"(例如 未整理)
2.把"收信匣"下的信移到上述自己新增的資料夾內
3.關掉TB
4.到自己的"郵局"資料所在找到"inbox.msf"跟"inbox(有壓實的這個檔會變很大)"
　　(不知道自己電腦內郵局跟檔案位置的就直接用檔名"搜尋"自己的電腦)
5.把"inbox.msf"跟"inbox" 都刪了 (不放心的就先備份出來吧)
6.打TB (應該是OK了)

PS:自己的感覺....直接在收信匣作壓實相當把"整個"信箱作壓實...結果好像越壓越大...囧...(有分類資料夾,其實每個資料夾都可以個別壓實,感覺個別壓實檔就不會出現"爆"天量的檔案大小了)