I have been using claws 3.8.0 on debian unstable for some time now, and I have noticed a strange network behavior when fetching messages from Gmail (imap). At first, when I start the program, messages download quickly, and the filter log displays many lines such as [23:37:07] IMAP4< [FETCH data - 1400 bytes] in rapid succession. However, after some time (of the order of hours, or after some idle time, I am not quite sure), Claws' fetch speed slows down considerably, and although the network log shows the same lines as above, they appear in a slow succession. The effect is that I am unable to fetch messages with large attachments, rendering the program unusable. Restarting fixes the network issue temporarily.
Does switching offline/online help ?
No, it just made the program hang. I had to kill -9 in order to open a new session, since the window became unresponsive when I tried to close it.
if this is still happening then re-open this report