The colors next to each email address indicate our estimation of the probability the email address is actually correct. It also comes along with an estimated confidence score.
The green color is provided for emails that are most likely to be deliverable.
The yellow color is associated with emails that are more risky and may bounce. These can be emails we haven't verified yet with a lower confidence score. We recommend verifying those emails with the Email Verifier tool.
They can also be accept all emails that we've already verified. Due to the nature of accept all emails, it isn't possible to know for sure if they are deliverable or not, but they can still have high confidence scores. You can find out more about accept all emails here.
Lastly, emails with a red color are most likely to be undeliverable (they are rarely displayed as we are constantly removing them from the search results).