How to lock the Mail app on a Mac
Short answer: macOS has no built-in way to lock a single app, including Mail. Apple's own Support Communities put it plainly — "It is not possible to lock apps individually." For most people the ask isn't about locking the whole Mac, just the one app sitting on years of correspondence.
Why people want to lock Mail specifically
"I don't want my entire computer password protected, all I want is my mail app"— Apple Support Communities
Mail is often the single most sensitive app on a Mac for a reason that has nothing to do with the emails themselves: it's where the "forgot password" reset link for almost every other account you own eventually lands. Anyone with an open Mail app can often work their way into your bank, your social accounts, and your work tools — one reset email at a time.
What doesn't work
A second user account means logging out first, which breaks the whole point of a quick handoff. FileVault only protects your data while the disk is powered off, not while you're logged in and Mail is sitting open. Screen Time can set a limit on Mail specifically, but that just means resetting a 1-minute timer over and over, and it's been documented as bypassable through Spotlight anyway.
What actually works
Shoo! locks Mail by ending its process the moment you lock it — there's no overlay to click past and no window left running in the background. It reopens only after Touch ID, Apple Watch, or a private backup password succeeds, and it works on Mail the same way it works on every other app, including ones Apple built itself.
Try it free for 7 days — full functionality, no credit card, $17.99 once if you keep it.
Frequently asked
Can I lock just the Mail app without protecting my whole Mac?
Yes — Shoo! lets you pick Mail specifically and leave everything else on your Mac untouched.
Does Screen Time work to lock Mail?
Not well as a lock. It can limit Mail to a set time per day, but you'd have to keep resetting a short timer, and it's been documented as bypassable through Spotlight — it isn't built for this.
Why is locking Mail more important than locking other apps?
Because password-reset and two-factor emails for most of your other accounts land there. Anyone with an open Mail app can often use it to get into your other accounts too, not just read your correspondence.
Can I open Mail with Touch ID after locking it with Shoo!?
Yes. Once Mail is locked it only opens after Touch ID succeeds. If your Mac has no Touch ID, you can confirm with Apple Watch (double-press the side button) or a private backup password that is separate from your Mac login password.
Is Mail still protected if I switch desktops or come back to it later?
Yes. Shoo! does not draw an overlay or check only at launch. It ends the Mail process when locked, so switching Spaces or returning to the app later can't show what was on screen. It reopens only after you verify.