Before activating the segment, it is a tip to send yourself a test email to see if the email is synced and if the data tags are correct. Send test mail by clicking on "Options" and clicking on "Send test mail".
If you get the test email to your inbox and everything looks correct, then you are ready to go!
Tips! Also check the email in your phone if you can access your emails there, a lot of recipients will surely read your emails in their phone!
Note that sometimes the test email may end up in your junk inbox because your email client think it looks weird when an email is sent from yourself to yourself in this way.