If you want to verify an email, send me a one-time code with several hours expiry that I have to resubmit through my logged in web identity at your site.
It drives me batty that a financial provider (retirement vendor from previous employer) won't seem to let my "paperless" setting remain active. Only because I don't ping their abusive email tracking pixels etc.
To me, paperless means I can log in and download my quarterly PDF statements and related documents, and they won't be left in a mailbox on the street. It doesn't mean I have to subject myself to reading your silly emails with a promiscuous client.