How to Add a Second User in Proton Duo (Easy Guide)

If you’re using Proton Duo, you get 2 separate user accounts under one subscription. That means you can create another mailbox (for example, for an accountant, assistant, or teammate) without paying extra. Here’s the easiest way to do it.

Step 1: Create a Free Proton Account

1. Go to proton.me/signup
2. Create a new account (for example: accountant@proton.me).
3. This will be the login for your second user.

Step 2: Invite the New User

1. Log in to your Admin account (the one that pays for Proton Duo).
2. Go to Settings → Users and addresses.
3. Click Invite user.
4. Enter the new Proton account you just created (accountant@proton.me).
5. Assign storage (e.g., 200 GB).
6. Send the invite and accept it from the new account.

Step 3: Add Your Custom Domain Address

Now you can give the new user an email under your domain (for example: accountant@yourcompany.com).

1. In Admin account → Users and addresses, select the user and click Edit.
2. Add a new address under your custom domain.
3. Save it.

Step 4: Activate the Address

1. Log into the new user’s Proton mailbox.
2. Go to Settings → Identity and addresses.
3. Find the custom address (accountant@yourcompany.com).
4. Click Generate missing keys → it will become Active.
5. Set it as Default so all emails use your domain.

🎉 Done!

Now you have 2 completely separate mailboxes under Proton Duo:

1. Your main account (Admin)
2. A second account (like Accountant), with its own login and custom domain email

This keeps work organized and secure while using just one Proton Duo subscription.