Anyone sending out notification emails or messages to a mailing list: put the recipient's name in the To field
Gmail's spam filter is pretty good, but sometimes it misclassifies messages. These are normally messages from commercial mailing lists -- I'm guessing other Gmail users have reported messages as spam rather than figure out how to get off the list, and this has resulted in Gmail deciding the list is spam. I've found one pretty good indication that something labelled 'spam' is actually real: it includes my name. So I have a gmail filter that forces anything with my full name in it to go into the inbox. So - if you're sending out notifications or mailing list messages and you have the recipient's name, please put it in the message! Ideally in the 'To' field, but it would be a good idea to stick it in the message body too.