From time to time I get the following message: "Unable to write the email to the mailbox. Make sure the file system allows you write privileges, and you have enough disk space to copy the mailbox." Yes I have tons of disk space. Yes the folders are regularly compacted. Now this is version 38.5.1 but I have INTERMITTENTLY had this problem with Thunderbird of other versions. I check multiple accounts and this problem seems to vary as to which ones come up with the error. I never used to have this problem. Yesterday it was fine. I just want a version of Thunderbird that is reliable and work. Also, I have AVG for antivirus if that is a factor. Thanks