I sometimes get emails that are obviously spam when I read the subject line. Rather than look at them, I delete them by Control-clicking the email and selecting Delete from the contextual menu. I can then go to my Trash folder in Mail and repeat the process.
Another tip: Beware that some emails can have hidden links. I have accidentally clicked in a blank area of an email and been directed to an unwanted web page.
Look for symbols substituted for letters, obvious misspellings, and spurious email addresses from the sender. I received an email, purportedly from someone I knew, that had wsorchesttra as the return email. Her correct address is wsorchestra (one t). The sender pretended to be this woman, asking me a favor if I could send money to a needy friend of hers. Naturally, I phoned her and she had been on the phone with AOL for two hours trying to resolve the problem (all her contacts had been hacked).
Be vigilant! There are lots of dirt bags out there with no conscience or morality.
macOS 10.15.5, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365