"Email Spoofing" is a form of hacking where the email "header code" is manipulated to make it look like the email originates from a known sender. 

This makes it more likely that the recipient will reply to a request for bank account information, a wire transfer, or other funds transfer.

Here is an example of what a "spoofing" email might look like:

Unfortunately, there is no way to prevent these emails from occurring.  Instead, you must exercise discipline when reading ALL your incoming emails:

Here are some suggestions on ways to identify these email spoofs:

• Check the "from" email and name.  Very often, they don't match.  But beware, sometimes they do match!
• Be suspicious!  Any email requesting funds or having anything to do with financial matters should be deleted immediately.
• View the Source Code to determine the true origination of the email.

If you suspect that an email is not authentic, you should:

• NEVER click a link or open an attachment from an unknown source.
• NEVER reply to these emails.
• Add a spam filter to your email program that filters words like "bank", "wire" "transfer" and "funds"
• Regularly scan your computer for Malware. I use Malwarebytes.com

I am initiating global filters for all my client email servers that can reduce the incidence of these email spoofs.  However, there is no assurance that I can delete them entirely.

Here are some additional sources on email spoofing:

What is email spoofing and how can I tell if my account has been spoofed?

Hackers are using a devilishly clever fake email attachment scam to break into people's accounts

What To Do When Your Email Gets Hacked