Most of the spam I get now specifies to “from” field as the same address as whoever is in the “to” field.
Is there a way I can make Qmail check all incoming mail to check whether the email address that the email says it’s “from” is actually supposed to come from that server? Or can I block all email from some domains if they’re coming from a remote server?
I did add an SPF record for my main domain a few months ago, but it doesn’t seem to make any difference