

get an email address just for spam, which you can mostly/fully ignore, and use your main email only for more important things.
alternatively, if giving them your email is completely unnecessary, use a throwaway like one of those “10 minute email” things.
i haven't tested the functionality below:
i think some services support writing your email as username+<text goes here>@provider.url
so you can do username+spam@provider.url
and the mail will appear in a separate folder in your email client.
yeah i think all government software available to the public should be free and open source.