It is recommend for you to have a secure connection network between your PC and the Gmail server. Let say if you login to Gmail using a public network like wireless or hotspot in Starbucks, someone can tamper or see the sensitive information transferred from your PC to the Gmail server. This is because the network you are using is not secure and is open to everybody.
Non-secure networks make it easier for someone to impersonate you and gain full access to your Google account, including any sensitive data it may contain like bank statements or online log-in credentials.
To check whether you are in a secure connection or not, check that the protocol that being used is https at the address bar. And also, there is a Lock icon at the bottom right corner of your browser (Firefox).
When you have both of them, that’s mean you are in a secure connection. No one can tamper or modify or spying on the data transferred between you and the Gmail server. You are now safe and secure to send emails, at least. More »