Thanks for your help!
I tested again and am still having the same problem. I’ll send a test email and a screenshot.
Yes, though in the sending account setup, I’ve got the “send emails via my website” option checked (the site has shared hosting). Could this be why it’s happening?
There’s an email link in the footer that’s working — I’m only having trouble with mailto links in the body of the email.
Never mind, fixed it by using an exclude shortcode.