If the mailing list is using a bulk email service, then they should use DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF) for identifying ownership & not getting marked as spam i.e. If they aren't really a spam.
Sorry, but your advice have been detached from reality for a long time.
SPF is not a "should" anymore, it is a must. Many major e-mail providers will outright reject your e-mail at SMTP level, unless you have correct SPF record. Rest will move SPF-less e-mail to spam on automatic basis. In this sense SPF does help you to get delivered, and avoid getting into spam bin, but your chances can only go from "100% spam" to "90% likely spam", not "0% likehood of being spam".
DKIM is not a major consideration for Gmail (or anyone, as far as I know) and have never been one. You will not magically avoid spam bin by using DKIM. Instead DKIM provides a great opportunity to botch your reputation with mail servers: as soon as you forward a e-mail (between providers or within the same provider) it will lose it's DKIM validity, and thus may get classified as spam (!!) on the basis of invalid DKIM signature. Boom! you are a spammer now.
Valid SSL cert and valid SPF are the only things, that have noticeable impact on Gmail's treatment of your email. DKIM and DMARK and largely useless and can only get you in extra trouble.
As for bulk email, it is going to be classified as spam until your domain and IP gain sufficient reputation. The only way to gain that reputation is to send slowly increasing amount of email for long time without being marked as spam. Being a rich business, Google's client, hanging on Google's forums, using Gmail as your mail server and having at least dozen contacts among Google's employees also helps.
