I understand why some folks use email whitelist blockers. Sometimes I wish I could get away with using one.
But if you send me an email first, add me to your whitelist if you expect a reply. I just received a very nice email to which I wrote a very nice reply — and got it bounced back to me because I hadn’t been whitelisted. There were instructions telling me how to get my message through. I haven’t followed them, and I won’t.
Nobody should have to jump through hoops to answer messages initiated by others. There just aren’t enough hours in a day.