What would it take to prevent email/phone spoofing, joejobbing etc?
There are numerous questions on MF and elsewhere about people having their email address or phone number spoofed by hackers/spammers, joejobbing, etc.
Why is it apparently so easy for hackers/spammers to spoof people's email address/phone numbers? More importantly, what would it take, technically, to totally prevent this? Is it something the phone companies or the email providers have to do or would it require completely changing the Internet/international phone system? And why isn't it done?