Everytime I email PDFs to my Kindle, I get a verification email with a link I have to click on. This same email says I can avoid this verification step by addin

Everytime I email PDFs to my Kindle, I get a verification email with a link I have to click on. This same email says I can avoid this verification step by adding the sending email address as an approved sender (or whatever) which I've done. But then also I've got these sent emails with large attachments to go delete. So it's a pretty clunky workflow.