[GTALUG] Spamhaus block

Does anyone has insights about dealing with Spamhaus? I'm getting increasingly frustrated by being listed without explanation. I run a very low bandwidth mail server and a website for my business. I am running postfix with SPF, DKIM, and DMARC. I'd like to know what I am missing. Spamhaus is very popular which in turn affects Twitter, LInkedIn, beyond just the mail. Is it possible to run one's own mail server this days?