Two Thunderbird profiles open at once on a Mac
Can you run two Thunderbird profiles at the same time on a Mac?
One Thunderbird profile holds many email accounts, which is usually enough. For two profiles open at once, each with its own accounts, address books and add-ons, Thunderbird has to be started from Terminal with --no-remote; Parallex makes the second one an instance you open with a click.
Keep work mail in a Thunderbird of its own, beside your personal one: its own profile, accounts, address books, calendars and add-ons, opened from Parallex, the menu bar or a shortcut.
How
- Install Parallex (below). Your Thunderbird isn't changed.
- Choose New Instance and pick Thunderbird. Name it for what it's for, like “Thunderbird Work”, and give it a color.
- Open it and sign in with the other account. Both run at once, each in its own windows, outlined in the instance's color.
Or without Parallex: every way to run an app twice on a Mac, compared.
What you get with Thunderbird
- Its own profile folder: Parallex starts Thunderbird with
--no-remoteand a profile of its own, so it runs beside your Thunderbird instead of handing over to it. - Window outlines in its color, and its name in the menu bar, so you know which mailbox you're writing from.
- Opened on its own: from Parallex, the menu bar, the ⌃⌥Space switcher or a keyboard shortcut of its own.
- Own identity, when you want it: a copy of Thunderbird with its own Dock icon and notifications, which Parallex keeps up to date.
Tested every night
Parallex's compatibility lab makes a fresh instance of Thunderbird 157.0.1 (the app itself, opened with a profile folder of its own, as New Instance makes it) every night on a clean Mac and opens it. On October 4, 2026, on macOS 26.6.2, it ran, and nothing reached the original's data. Its instances have run clean on all 2 nights since October 3. Made as its own copy instead (Own identity), it ran clean too. See every app's latest result.
Good to know
- The instance is Thunderbird itself, so it shares Thunderbird's Dock icon unless you turn on Own identity; its windows are outlined in its color instead.
- The new profile starts empty: add the mail accounts it's for, or copy them over with Thunderbird's own export and import.
Questions
Doesn't one Thunderbird handle several accounts?
It does, and for most people that's enough. A second profile is for keeping one set of accounts, address books, filters and add-ons entirely apart, both open at once.
Can I do it in Terminal instead?
Yes: open -n -a Thunderbird --args --no-remote -P <profile> starts a second Thunderbird with another profile from Thunderbird's own Profile Manager. Parallex does the same thing with a click.
Get Parallex
Free to try, for macOS 14 and later. In Terminal:
curl -fsSL https://parallex.mandip.dev/install | shOr download the disk image, or with Homebrew: brew install --cask mandipadk/parallex/parallex. Then choose New Instance, pick Thunderbird, and give it a name.
Already have Parallex?
This opens New Instance with Thunderbird picked; you name it and choose its color.
Make a second Thunderbird