Need gmail/spam help, please.

1. Typical email is "lowes gift certificate" or it will say "no sender" but it is a $500 gift card, etc

2. The address it comes from is the obvious spam/unsafe type email that I know to look for.

3. I click on report spam and unsubscribe, but to BLOCK them I have to OPEN the email first, I never open them, let alone click on something inside.

4. I have disabled in "images" - and checked following - "ask before displaying external images"

If I OPEN the email only to BLOCK it, am I at ANY risk? I use both a PC and iPhone.

And HOW do I block them from getting them in the future, I get WAY too many in my regular email.

Thanks...