Received spam email from my domain

I have quite a few different domains configured and haven’t run into any problems sending or receiving mail before, and all the system checks are error-free, but when I checked my spam folder recently I found an email that had it’s from address spoofed to one of my domains. I deleted the domain in question from my server (I barely ever used it), but i’m wondering if there’s any way I can prevent this? It was in the spam folder, however it was an incredibly convincing fake. All DNS was handled by mailinabox, I didn’t made any changes.

There aren’t a whole lot of options that I can think of, and the ones I can think of would be at least partially unsupported.

For example, changing your DNS records is supported, so you could change your DMARC record to p=reject.

Changing configuration files in MiaB is generally unsupported. You could configure /etc/opendmarc.conf to block DMARC failures by setting RejectFailures true (note that MiaB is configured just for the default, which is false).

However, note that this is a global change that will be applied to all inbound email, and you will soon discover how poorly the other guys are at configuring their DMARC records.

It will also affect your domains when sending mail from other servers, so you have to take care and be sure all of your DNS records are correct, or you’ll be just like those other guys.