Touching that file did not make a difference. By chance (?) the file was dated 10 calander months ago, to the day the problem started.
I have enabled verbose mode in /etc/fetchmail. The only extra information it includes in the e-mail is:
#**********.********.*******.************.***
That's verbose alright, but in *whispered tones*. Unless someone understands a message hidden in Morse, I don't think this is very useful.
There is one entry in /etc/fetchmail that relates to mail filters, and that is at the end of one of the pop-mail entries:
preconnect "/usr/bin/mailfilter --mailfilterrc /etc/mailfilterrc"
The file /etc/mailfilterrc is empty. Could that be the problem? If I remove the pre-filter line (and find out what is putting it in) then would that solve the problem. I assume if the mailfilterrc file is empty, then it can't be doing much. I'm not sure why it is just on one of the pop-mail entries, and on nothing else.
-- Jason