Hi Tearinghair
As Tuvok has suggested, use something like Mailwasher, which comes with both a free and professional version, especially if you use a client program such as Thunderbird. I have used the free version for many years for my various emails accounts, and all spam of the sort that you are being plagued by is intercepted and sent to spam folders automatically, no matter what the senders domain or name is, Mailwasher picks them up probably by the nature of the content.
You can also set up 'Friends lists' for senders you wish to receive no matter what the content, or 'Black lists' for senders that seem to get through the normal filters but you wish to block.
I'm not sure if Mailwasher works with emails viewed via web browsers, but I have realised that whenever I pick up my emails on my Android mobile phone, or my I Pad, no spam messages appear, as if Mailwasher is working in the background all the time, even though it is only installed on my desktop PC.