A lot of our processes work on a quarterly (every 3 months) cycle, and we'd like to use campaigns to send emails based on that. 

I'd like the option to send (the same) emails every three months.

I was hoping that the cyclical autoresponder would allow that, but it seems to only allow "every 1 month", not "every x months". Quarterly is also not an option.

Given this, what's the best work-around?