This is a really great topic. Most spam is very easy to spot. There are only 2 tricks, 1st is remembering to look to see if it is spam before clicking any links, and the 2nd is knowing what to look for.
Now that you remembered to not click any links and you want to verify if the email is spam, the first and simplest thing to do is to look at the FROM address in the email.
Email is addresses have to parts name@domain-name
Name doesn't matter much, it can be dan@ or it can be no-reply@, sales@, anything. That just tells you who@from-where-is-this-email-coming-from
Now you are looking at the Email address in the FROM, look at what is to the right of the @ sign. That is the critical piece.
To the right of the @ is the domain name. In my case, that's eecons.com. In case you see the term TLD, which stands for Top Level Domain, that is the part to the right of the . (period).
.com .net .org .us .uk .ly - these are all TLDs. Together with the what is to the left of the . (period) combined with the TLD makes the entire domain name.
So, for instance, amazon.com and amazon.net would be 2 different domain names and don't need to be the same company.
For instance, ford.com may be the car company yet ford.us may be a jewelry store. You must take the entire name, both sides of the . (period) together.
Note, there is no difference email addresses between upper and lower case letters, so AmazoN.com is the same as amazon.com.
Now going back to the problem of knowing if you have received spam email.