Originally Posted by
segfault
Note that when sending an email through SMTP the sender can set any From: address they like. So if you get a SPAM email supposedly from a friend, it is unlikely to be coming from their email account. Instead it is from the spammers email account, using a forged from address.
Those are easy to spot as the reply to address is never the same.
Any proper email system can detect forged addresses as there are mechanisms that identify it originates from an unauthorised IP address.
The majority of email compromises, Like Dennis', take control through phishing campaigns that spoof their ISP/email provider communications.
You see it all the time for banks, well known email service like 365 or big ISP's like sky.
A popular one will warn you of unauthorised access on your account and asks you to log in to verify it is correct. There are variations on the theme.
It is becoming less popular to install bad software as that is much easier to detect these days.
Sky seems to be the old yahoo email service, who have more holes than an old pair of knickers.
Would be the last service I would rely on for secure email.
You'd be better off with google or a personal 365 account.