Shared Mailboxes: One Inbox Your Whole Team Can Open

How it's different from the alternatives

• vs a normal mailbox — a normal mailbox is one person with one password. A shared mailbox is many people, one address, and no password to hand around.
• vs forwarding — forwarding copies incoming mail to someone else, but their replies still go out from their address. In a shared mailbox, replies go out as the shared address itself, so the customer only ever sees support@yourdomain.
• vs an alias — an alias is just another address that lands in one person's inbox. A shared mailbox is its own inbox that a whole team works out of together.

Create one

Go to Mailboxes, click Add mailbox, and under Create directly pick the Shared option. Give it a name (e.g. support), choose who's on the team, and create it — no password is ever asked for or shown, because nobody logs into it directly.

Already have a mailbox you want to turn into a team inbox? Open its … menu on the Mailboxes page and choose Convert to shared mailbox. Converting rotates the old password so it can no longer be used to sign in — from then on the inbox is reached only through its members.

How your team opens it

Members don't get a separate login. Each person opens the shared mailbox through their own account. In webmail, the sidebar has a Shared mailboxes switcher — click the team inbox and you're now reading it, with a banner showing which mailbox you're in. Reply or compose and the mail goes out as the shared address. Click back to return to your personal inbox anytime. Because everyone works through their own authenticated session, each person's own password and two-factor authentication still protect access.

Want to rename a team inbox to something that makes more sense to you? Hover its row in the switcher and click the pencil to set a personal label. It's stored per person and shows only in your own switcher (and your unified inbox) — it doesn't change what anyone else sees. Clear it to fall back to the mailbox's name, then its address.

Use it in a desktop or mobile mail app

A member can also use every shared mailbox they can read in Outlook, Apple Mail, Thunderbird, the Gmail app, and other standard IMAP clients. Connect the member's regular mailbox once with that mailbox's own address and password. The shared inbox then appears at Shared/<shared-address>/INBOX; do not add the shared address as a second account and never try to authenticate with it.

Members marked Can reply may select the shared address in the message's From field and send through TrekMail SMTP while still authenticating as themselves. Read-only members can open the delegated folder but cannot change its messages or send as the shared address. Removing a member revokes both webmail and mail-app access.

See Use a Shared Mailbox in Outlook and Mail Apps for server settings, folder subscription, Send As, and troubleshooting.

The unified inbox

Once you're on at least one shared mailbox, a Unified entry appears at the top of the switcher. It merges your own inbox and every shared mailbox you can read into one date-ordered list, so you can keep an eye on everything in a single place instead of clicking between inboxes. Each row carries a small coloured badge of the mailbox it came from — hover it to see the mailbox name and address — and when you reply or forward, the message correctly goes out from that source mailbox.

The unified inbox is for reading. Cross-mailbox text search and multi-message bulk actions aren't available there yet, so the search box and the bulk-action controls are hidden while you're in it — open an individual mailbox when you need to search or act on several messages at once.

Managing who has access

Open the shared mailbox's settings (the Manage button on its row) and go to the Access tab. It lays out everything in one place: People with access lists everyone who can open the inbox, each with a one-click Remove; Add people is a searchable list of the other mailboxes in your account — tick anyone you want and add them all at once.

• Everyone can read the inbox. By default they can also reply (send as the address); flip someone to read-only on the Access tab if they should follow it without sending. That's the only permission to think about — there are no other roles.
• Removing someone takes effect immediately — their switcher entry disappears on their next load.
• A shared mailbox always needs at least one person, so you can't remove the last member. Add someone else first, or delete the mailbox if the team is done with it.
• If a shared mailbox ever ends up with no members (for example because the last member's mailbox was deleted), the Mailboxes page flags it with a “No members” badge so you can add someone back.

No shared password, by design

A shared mailbox can't authenticate directly — not through webmail, IMAP, or SMTP. There's deliberately no password to share, so there's no shared credential to leak, rotate, or forget when someone leaves the team. Native mail-app access is delegated through each member's own IMAP/SMTP login; it does not turn the shared address into a login. Removing a person from the Access tab is the whole off-boarding step. That's also why a shared mailbox has no Security or password tab in its settings. If you later need it back as a personal mailbox, the Access tab has a Convert to a regular mailbox option — it removes the members and lets you set a fresh password so someone can sign in directly again.

Plans & limits

• Shared mailboxes are included on Starter and up: 5 per domain on Starter, 15 on Pro, and 30 on Agency.
• A shared mailbox also counts as one of your regular mailboxes on that domain, so it draws from the same per-domain mailbox cap and storage pool.
• The people you add as members can be on any domain in your account — a shared support@brand-a.com can be worked by people whose own mailboxes are on brand-b.com.

Automating it (API & MCP)

The whole thing is scriptable. Over REST, GET /api/v1/mailboxes/{id}/members lists who has access, POST the same path adds someone, PATCH …/members/{member} flips a person between reply and read-only, and DELETE …/members/{member} removes them. You can also build the inbox itself from the API: POST /api/v1/shared-mailboxes creates a brand-new team inbox, POST …/mailboxes/{id}/convert-to-shared turns an existing mailbox into one, and POST …/mailboxes/{id}/convert-to-regular turns it back into a normal mailbox with a fresh password. GET …/mailboxes/{member-id}/client-setup returns that member's server settings plus their delegated shared folders and permissions. AI agents get the matching lifecycle and member tools, while get_mail_client_setup exposes the same native-client discovery. They all reuse your existing mailbox API scopes — see the API overview for authentication and the request shape.