When it comes to email accounts, some are registered for temporary use - and are pretty much expendable - whereas some accounts are used to contact family, family, or are used commercially and it is essential that they are safeguarded and kept secure.
It is fairly common - even with increased security - that many webmail accounts and email accounts are compromised and person's with "ill intent" gain access. The purpose of hacking/tampering an email account is usually to send spam/phishing emails from it, although, persons with a close relationship to the account owner may wish to tamper with the account out of malice/financial gain.
There are some common sense safeguards you can employ in an attempt to protect your email account:
1) Restrict access to your computer: password protect your user account in Windows etc.
2) Run anti-virus, anti-malware and anti-spyware programs on a regular basis.
3) Change your account password and security question weekly: keep the details in a secure location. Make the password strong: lower/upper case letters, numbers and over 8 characters.
4) Sign-out of your account and close the browser window when finished. Check the activity log of your account every week.
5) Do not download unknown attachments or click on hyperlinks in unknown emails. They can often include viruses and worms etc.
6) Make sure your security question cannot be guessed by family, friends or work colleagues.