Anti-Spoof refers to a sender who is looking to fool your users to clicking links which look legit, however redirect to another site. Most commonly spoofing refers to an email which looks authentic and to have come from someone you already know, when in fact the from address has been made to look authentic while being sent from another source. This method is especially vulnerable for mobile users, as most mobile devices only show the display(from) name vs the full email address.
Gradually rolling out over next few months.
Spoofing from an existing address builds trust as it looks like an email you know is authentic and will open, so it’s especially enticing for a scammer to add links or related that you will either click and/or respond to their request. This comes in many forms, could be made to look like a legit password reset request where you will click the link and enter credentials, once completed then your details are now in the hands of the scammer.
Of course this is only one example as you can imagine there would be many scenarios which can apply for links and obtaining important credentials, details…etc. Therefore it’s important to capture the email prior to making it to the users inbox, with enhanced anti-spoof protection an email being received is checked against a number of elements for protection building on top of existing email authentication standards (SPF, DMARC, DKIM).