Why does this message keep popping up? "The messages you have deleted can be purged from disk. This operation will save about 258 MB of disk space. Select the option below to let Thunderbird do this automatically without asking you." I don't want Thunderbird to do this automatically without asking me. But there is no option to make it my choice. I can "empty trash" any time, and I do. How is this pop-up offer different from that. I did click to have Thunderbird do this -- once. But the pop-up continues to appear every time I click to delete a message. Surely Thunderbird "saved" all those megabytes of disk space the first time I had it do so. Why does this message keep popping up?