Migadu rocks, it’s a paradise for email custom domains. Can’t get better than this. https://drewdevault.com/2020/06/19/Mail-service-provider-recommendations.html

That is pretty cool for folks that want a quick and easy way to block ads.

You’re right. My point was that Pi-hole made me appreciate the Firefox forks more because the plain Firefox is FULL of GOOGLE!

Yeah. I thought about that. When you add an icon to your rows of shortcuts in Firefox and it fails to fetch the correct icon and gives it a generic letter instead and you want to add an icon yourself you cannot just upload or insert an icon to your Firefox, you will need to point it to some web link where the remote icon is. I can imagine Firefox wants to check at each startup whether the remote icon has changed or not (Not completely unreasonable. Think about Twitter changing to X).

I see. When you wrote :

email from their devices from Gmail domains

I assumed that the customers were sending it from GSuite based custom domains, but this is plain gmail.com and that makes the DMARC part different. Did your company make any DNS changes just before this happened ? SPF records have a maximum length they can have. If it exceeds the maximum length, it can cause failure and email rejections.

Dropped as spam because of DMARC failure ?