You could take a look at the Error console (ctrl-shift-j).

Thank you Ed. I did not find anything in the Error console that could direct me to the specific error and the email account causing the error.

Your suggestion has also led me to "Activity Manager". I will check both "Error Console" and "Activity Manager" the next time the error occurs.

In your mail account, any emails that get 'forwarded' by the filter, should have a right curved arrow next to them positioned to the left of the Subject. If you also enable 'threads', you can see what was actually forwarded and to whom. Anything that did not get forwarded may not have those set against the email.

This might help to locate the email and then you can check with Message Filter to see what email address it should have been forwarded to.

In 'Message Filters', did you create a filter to auto 'Forward' mail ? If yes, you could check the 'Filter Log'

First make sure it's been enabled. In 'Message Filters' for the account that forwards the emails. Click on 'Filter Log' button Top left - is the checkbox 'Enable the Filter Log' selected ? If no then select it now. Click on 'Close'

That filter log will display, date and time, name of filter applied and also a lot more info about which mail got filtered. It should be reasonably easy to search for the relevant filter name. Data is just text, so can be copy pasted to another program to facilate any type of search.

You can also clear the log every so often, so it does not get enormous.

Where is the data actually stored: In the profile folder the file that keeps a log is the mail account name folder and is called 'filterlog.html' which you can open using eg: Notepad++ or OpenOffice Writer or even in a browser.

Toad-Hall, thank you for your very thorough response. I have now enabled the log files for all filters that are automatically forwarding email. If or when I get the next error message, I will check each of the log files.

It would be so much simpler if the error message would include the email account name from which the error occurred.

Thanks again.