You are not penalized for sending infrequently but sending infrequently lessens the chance that your recipients will remember you and remember why they subscribed to your emails and if they don’t remember, they mark as spam.

The problem for Font Awesome is 2 fold:

1. Kickstarter spam is a huge problem, seriously, it is so prevalent I expect gmail may even have specific rules around it. There is an entire cottage industry of kickstarter “promoters” that send out so much spam.

2. Font Awesome… is not a kickstarter? They’re using their email list to advertise a new project, Build Awesome. Same team, similar ethos, sure, but it is entirely new — they are sending email about a project to people who didn’t subscribe to email about that project.

Who knows why specifically their email performance is so bad, but this blog post doesn’t come close to providing plausible explanations.

an old quote .... ".. having mastered the game of five card stud in the Pacific theater, the victorious Allies declare the game of Poker to be illegal"