We've starting to receive bounced spam messages and the sender is one of our email address. We know that we don't send spam from that address. We've tried changing the password but we're still receiving these bounced emails.
Note: This email account is not configured in an email client. We only access it through the browser, using HTTPS.
How do we prevent spammers from using our email address to send spam? I've googled around and almost every website says that forging the "From" address is pretty easy using an email client and it is impossible to stop these kind of spammers.
Note: We're using the email functionality in a shared hosting account, not hosting an email server ourselves. Even the tech support says Not a whole lot we can do about stopping that.
Best Answer
Short Answer: You can't.
For more info, this gives a basic explaination as to why.
This shows how easy it is to do. It's just the nature of SMTP, it's insecure!
Just because an email appears to come from somebody, it doesn't mean it did.