What gives, Sierra Club?

I’ve been getting a lot of literature from Sierra Club lately, and this has me a little perplexed. Obviously, nonprofits are very much in the business of begging for money and volunteers. This doesn’t surprise me, nor does it bother me. What vexes me is that everything I’ve gotten from Sierra Club over the last 12 months has been in the mail. This creates paper waste and uses fossil fuels.
Like people with even a passing interest in conservation, I’m familiar with Sierra Club. After all, it’s one of the largest, oldest, most widespread environmental groups in the US. There’s no confusion about how to make a donation, if the notion should ever strike me. But why would I donate to an environmental group that seems to be so wasteful?

Image source: National Park Service