Email is stored on the many servers it passes through while in transit over the Internet (these servers are called "relaying hosts"). Some servers store your email messages for many years. You can never be sure if your message has been deleted. Stored email can be stolen and read by others from any relay machine that has a copy of your message. 

Anyone - including those who may have malicious intentions - can often gain access to your email messages if they know your email address.

Email is also tracked through the many servers it passes through while in transit over the Internet. Because your real identity is known to your ISP, your email can be traced to you by your ISP. Your ISP may voluntarily disclose your email and/or real identity to third parties, or may sell or trade your email and real identity to third parties. 

Wait, it gets worse.  It is extremely easy to forge an email address - anyone with a decent email program can do it.  You cannot tell if the person who says they're the sender is in fact that person.  Just imagine if someone posing as you sent an email message to a loved one convincing them to meet "you" somewhere - the results could be tragic.  Unfortunately, it happens all too often.

The bottom line: you need an email solution that gives you undefeatable security - you need BetterEmail (click to learn more)