Mail that named no face took the reader's system-ui, which is the app's own face: monospace, since parcel took Omarchy's look. Beside mail that names Arial at 14px it read far larger and wider. Plain text mail, made HTML, did too. Give such mail sans-serif, as mail is written for and other clients show it, and make code and preformatted text an eighth smaller, once, since monospace runs wider than sans-serif at one size.