tmprules-xx.dat files in /tmp

[KS <lists04@fastmail.fm>]

Hi,

I have noticed that there are always several tmprules-xxx.dat (xxx is a
string of numbers) in my /tmp. They are made every 5minutes and each
files contains the following text:

version="8"
logging="no"

I think Thunderbird is making these files. But is it normal to have
several hundred files (now I have 550) containing the exact same text?

Thanks,
KS.