re: The "Incoming mail" folder can not be compacted due to a writing error. Make sure there is enough disk space and you have the right permissions' There could be a couple of reasons, but if the Inbox is corrupted then you may start to lose emails. Please do the following: * Move all wanted good emails out of the 'Inbox' and into other suitable folders for organising and storage. Do not put in a subfolder of Inbox. When you have moved everthing you want to keep..... Make hidden files and folders visible: * http://kb.mozillazine.org/Show_hidden_files_and_folders In Thunderbird * Help > Troubleshooting Information * click on 'show folder' button a new window opens showing the contents of your profile name folder. * Close Thunderbird now this is important. Pop mail accounts are kept in the 'Mail' folder. Imap mail accounts are kept in the 'ImapMail' folder. Assuming this a POP mail account * click on 'Mail' folder * click on pop mail account name folder Delete these files: 'Inbox' mbox file with no extension - this contains emails, but in your case you have moved everything you want to keep. 'Inbox.msf' file. This is just an indexing record of the 'Inbox' file. * Close window - top right x * Start Thunderbird. A new 'Inbox' and 'Inbox.msf' file will be created.