User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

Steps to reproduce:

Dear Ladies & Gentlemen
This is not an error report but a recommendation:
I receive often the same scam in ALL my email accounts.
Perhaps you could make a filter that filters all email accounts
instead of only the account one where the filter is installed.
Thank you for your time to read this
B Rgds from Málaga in Spain
Manfred Leister

What you are asking for is bug 34973

But there is also junk mail processing, which already covers multiple accounts. See https://support.mozilla.org/en-US/kb/thunderbird-and-junk-spam-messages