My inbox has recently been getting several spam emails every day that have been spoofed with my own email address as the sender. Obviously I don't want to block my own address in Sonic's blacklist settings, but is there any other way to reduce such spam? Blocking by subject keywords is a possibility, although words like "reward" and "congratulations" and "survey" could show up in legitimate email messages, too, so that approach is dicey.
We do block millions of spam messages daily, including many that are "From" your own email addresses. You can tweak the anti-spam system scores if you want it to be more aggressive, but that causes some risk of blocking legitimate emails. The system errs on the side of caution in regards to that.
Email is unfortunately not inherently trustworthy. Like a postal letter's envelope, anyone can write anything they want to as the "From" address. The internet has many components like this, leftover from a kinder, gentler past.