Email differed by one character
This is a problem that could be easily fixed in email clients. If you get an email from a 'new' address, make sure that fact is highlighted. That way you can't be fooled by someone trying to spoof via a similar address, even unicode based attacks where another version of an 'a' that looks identical couldn't pass that by.
So if the person responsible for wire transfers an email that was highlighted in yellow so they knew it was from a new address, they would have immediately known it was a scam. Failing to accept that email address would result in subsequent emails being highlighted in red (substitute your own colors or method of making sure the fact the email address is not already known to the client)
There are obviously ways to fully spoof email addresses, though thankfully that has been getting more and more difficult to accomplish due to various measures taken in mail servers over the past decade or two (SPF, DMARC, etc.) Now clients need to start addressing gaps on their end.
Even the average person could benefit from this, if they see one of those spam emails telling you that your Amazon Prime renewal could not be processed and you need to update your payment methods they would have the potential to consider the possibility of it being a scam since it would show up as a new email address rather than being from one of the Amazon addresses you'd already approved.