I have been using Thunderbird for about 5 yrs and I strongly prefer it to Outlook. However, my PC has a small solid state drive (128 GB) and Thunderbird is creating very large files. The first time this happened I uninstalled Thunderbird and then reinstalled it and picked up about 20 GB on the hard drive. I have always installed it with the standard selections. When space became short again, I started deleting or moving files and applications. I would free up 15 GB, but the next time I booted up, that space would be gone. Using WinDirStat, I found a folder in my Users/myname/appdata/roaming/Thunderbird that was 70GB, more than 1/2 my drive. As info, the total space used for email on the Gmail server was only 13GB. I uninstalled Thunderbird but only picked up a small amount of space. I manually deleted the Thunderbird folder and picked up 70 GB in storage. Outlook seems to have no such folder, I also learned that deleting an email message in my inbox folder does not delete it from my Important or from my All Mail folders and most importantly the Gmail server. I was suprised to find that the all mail folder on the server contained nearly 200,000 messages. The only way to delete them was going to gmail using a browser and deleting them directly on the server. I would like to return to Thunderbird if these problems can be resolved.