It's the American Red Cross. If you've donated blood before, they're calling to see if you're interested in donating plasma. I said I was only interested in the whole blood donation and was taken off the list.
To make the Red Cross stop calling for blood visit the Red Cross blood donation site, find or establish your profile, and somewhere in there is a spot where you can check for them to not call you. I did that years ago. I still donate, and I open emails from them, but I made them stop calling.
They call often because there is a continuing shortage of blood. Between AIDS and Mad Cow and Zika an awful lot of people can't donate. There are a couple of illnesses spread by sand fleas in the desert so military people who have spent time in the middle east can't donate. Many older Americans are on blood thinners or medication for enlarged prostate and they can't donate.
Please donate if you can. I've been donating for 40 years. My donation 2 weeks ago was #138. If I can do it you probably can, too.