How it works
Email sub-addressing, explained
Sub-addressing lets you create unlimited variations of your email address with no new accounts. Subaddressify automates the whole process.
The anatomy of a sub-address
Local part
The part of your email before the @. Stays the same across all sub-addresses.
Date stamp
Today's date in ISO format. Tells you exactly when you signed up on this site.
Hostname
The domain of the site, formatted as slug. Uniquely identifies where you registered.
Step by step
Install Subaddressify
Add the extension from the Chrome Web Store. On first launch, click the extension icon and open Settings to enter your real base email address. This is stored locally in your Chrome profile and synced across your signed-in devices.
Visit any website
Navigate to any site where you need to provide an email address — a checkout, sign-up form, newsletter, or any registration flow. Click the Subaddressify icon in your Chrome toolbar.
Your unique address is generated
The extension reads the current hostname and today's date and computes a unique sub-address in the format: localpart+YYYY-MM-DD-hostname-tld@domain.com. Everything is computed locally — no server calls.
Copy or auto-insert
Click Copy to put the address on your clipboard, or click Insert to automatically fill the focused email field on the page. The address is ready to use immediately.
Set up inbox filters
In your email client, create filters that match the sub-address pattern. Apply a label, route to a folder, or set up automatic deletion. Because each address encodes the site and date, your filters are precise and future-proof.
How sub-addressing actually works
Sub-addressing (also called plus addressing or tagged addressing) is defined in RFC 5233. The email standard allows anything after a + in the local part of an address to be treated as a tag. Your mail server strips the tag and delivers the email to your main inbox.
This means you+2026-05-04-netflix-com@gmail.com and you@gmail.com are the same destination. Gmail, Outlook, ProtonMail, and Fastmail all implement this natively. You can use any tag you like — Subaddressify just makes generating a consistent, meaningful tag automatic.
Because the tag encodes the site and date, you can filter precisely. A Gmail filter on to:you+*-netflix-com@gmail.com catches all emails from Netflix registrations, regardless of when you signed up.
Setting up filters in Gmail
- Open Gmail and click the search options icon (⊞) in the search bar.
- In the To field, enter your sub-address (e.g.
you+example-com@gmail.com). - Click Create filter at the bottom of the search panel.
- Choose what to do: apply a label, skip the inbox, mark as read, or forward elsewhere.
- Click Create filter to save. All existing and future emails matching that sub-address will be handled automatically.