My new iMac runs Mojave; my old iMac never moved off High Sierra, which I felt was a fine version of macOS. Now that I have no choice but to use Mojave full time (I have it on my laptop for work purposes), I'm finding some annoying changes. Amongst those annoyances, this one is—by far—the most annoying…
That's a set of messages in Mail, as viewed in Classic View mode (using San Francisco Display at 15pt on both Macs).
Somewhere in Apple, someone thought it'd be a great idea to reduce the line spacing in Mail—only when using Classic View, which is my forever-preferred view. Maybe they're doing this to force us to upgrade to the modern view?
Please, someone, tell me there's a hidden pref for line spacing in Mojave's Mail Classic View? If not, well, come on, Apple, give me back my whitespace!
Update: The compacted line height bothered me so much that I tested every font in my collection tonight, trying to find one with better vertical spacing. Thankfully, vertical spacing does vary by font, though most of mine were way too tight. But in the end, I found one that works for me: Sukhumvit Set Medium at at 15pt size. Here's the screenshot from above, but with Sukhumvit added in:
This font is bundled with macOS, to the best of my knowledge—it's an iOS font, and I imagine macOS includes it (along with other iOS fonts) so that Marzipan apps will work as expected. But who knows—maybe it's installed with Xcode. Whatever the reason, this font is a near-perfect replacement for San Francisco. It's not quite as crisp and clean, but the line spacing is much more to my liking. (It's actually a smidge more than I had in High Sierra, but not so tall as to look weird.)