My confidence is also very low.
It is also important to understand that the bad guys are very aware security software, including spam blockers/filters are working hard to detect their spam by looking for patterns, trends, malicious activity, keywords (including email addresses, domain names, etc.). Consequently, the bad guys are constantly changing those patterns and keywords in their attempts to stay 1 step ahead of the spam blockers.
MailWasher is excellent at learning to detect spam directed at you, but no spam filter is, or ever will be perfect. That is why spam has been around since the late 1970s and really proliferated when the so called "legitimate" spammers (commercial marketing weenies) started mass mailing ads (whether we signed up for them or not) to millions and millions of people.
If it was easy to stop all spam, it would have been done decades ago.
In my opinion, there is no better spam blocker than MailWasher Pro - and I've tried many. There is a bit of a learning curve to it, but given time, it is well worth it. One of its greatest strengths is the fact it, by default, only downloads the first few lines of the source/header information and message content, and not the entire message. This is a HUGE advantage as that is typically enough information for MWP to determine if good or spam, and more importantly, it gives us users enough information to determine if we want to keep it or not.
This means we can, essentially, process all our emails
on the email servers from MWP, instead of downloading them completely on to our systems (including any potentially malicious attachments), and then analyzing them for any malicious code as other spam blockers do. That's a very good thing!
I liken other blockers to home owners who invite the stranger into their homes and THEN asking what they want. Whereas MWP is like verifying credentials and intent through a locked gate, out front of the home.
Another problem with all blockers is the potential for false positives - good emails tagged as spam. My primary email provider, gmail, is good and bad about that. They do catch 100s and 100s of spam regularly. But they also regularly tag good emails as spam and sadly, they will automatically delete those after 30 days. This means every 2 - 3 weeks, I have to visit my gmail spam folder and tag those as good. I typically end up creating a filter in gmail to let emails from those senders through.
My secondary email provider, my ISP, is also bad in this regard - frequently tagging good emails as spam.
If I did not manually change the defaults to let those emails remain in the inbox for MWP to fetch, I would never see those as my ISP would move them to a spam folder, out of reach of MWP.
It is very rare that MWP tags a good email as spam. But when it does, it is simple for me to verify, one way or another, and if good, retag it as good (which forces the learning process to learn - another good thing).
Because MWP lets me poll my various email accounts on different email servers, and displays all those in one place (the MWP Inbox) I can easily process all my emails from one place - WITHOUT actually downloading all those emails (including the unwanted emails) to my local machine. This is a HUGE advantage.
The vast majority of "legitimate" emails I get, I don't need to keep. For example, most of my emails are forum or reply notifications, deposits or debit notifications to my bank accounts, Amazon order delivery dates, and sale ad at stores
I signed up for, I can view those and learn what I need to know. Then mark them for deletion by MWP. Then when I tell MWP to process my emails, only those few I want to keep actually get downloaded completely to my system and end up with my local email client (Office Outlook - in my case).
I personally am not a fan of using Blacklists (or Friends lists), so I don't. I don't use Blacklists because as I noted above, the badguys are constantly changing their spam to avoid detection. I do, however, have over 2 dozen Filters (including one for Friends and another for Family - this is why I don't need to use the Friendlists). I have enough filters so, of the 50 - 60 emails I get daily, almost all are tagged by one of my filters.
If there is one that is not, I can easily see immediately if it is legit, or suspicious.
This method works great for me, but you may prefer a different method. And MWP allows that.
So give it time. Play with filters (there are some real pros here willing to help you with that). But still, you need to accept some spam, will always get through. But over time, those numbers will continue to get smaller to the point you will go days without any.