How to block spam email that is spoofed to appear as if it originated from my own email address?

For the most part, I send/receive Comcast email using the stock email client on my Samsung S9 mobile phone. Generally, when I receive a spam email, I utilize my email clients 'mark as spam' function. However, increasingly, the emails (from) address is spoofed to appear as if it originated from my own address. So, if I were to  select the 'mark as spam', I would be blocking my own address. How do I permanently stop this spoofing? When I utilize my PC/Thunderbird email client and I choose 'view message source' I can see 'return path/envelope-from' that shows what appears to be the true spammer email address. I imagine that I could then take that email address and utilize Comcast webmail to add that spam (?) but that doesn't seem practical in a mobile world. Any tips? Thanks in advance.