Google is really pissy about things that they consider against their little worldview. I used to have an address I kept for link aggregation, sent to me from me. I noticed one day that a lot of emails from sites that I know were still active weren't showing up in the inbox. Checked spam, they're all there listed as "You reported this as spam." I did no such thing, and hadn't even logged into the web interface in the better part of a year. Dumped the gmail account, went to a private domain account, and the only time I get a no-send is when the RSS feed gets malformed and the scraper dumps garbage - the sending entity goes "that don't look right" and rejects it.