Wolfgang: I also observed this "TB redownloads either 30 or 50 messages" with the gmail account that Connor gave me, and I have one possible explanation. During the initial download with the debug version, I can see a number of cancelled downloads due to failures to acquire a folder lock here:
c:/tb/beta/src/mailnews/imap/src/nsAutoSyncState.cpp, line 643
After some period of time, there were additional attempts to download messages from folders that I thought were already done, and it is possible that those earlier failures were being downloaded. I have not fully confirmed that this is the cause, but it is a possible explanation.
Wolfgang: I also observed this "TB redownloads either 30 or 50 messages" with the gmail account that Connor gave me, and I have one possible explanation. During the initial download with the debug version, I can see a number of cancelled downloads due to failures to acquire a folder lock here:
c:/tb/beta/ src/mailnews/ imap/src/ nsAutoSyncState .cpp, line 643
After some period of time, there were additional attempts to download messages from folders that I thought were already done, and it is possible that those earlier failures were being downloaded. I have not fully confirmed that this is the cause, but it is a possible explanation.