Plus Addressing: The Free Email Trick Most Businesses Aren’t Using

A client asked me last week whether plus addressing was worth turning on for his team. Short answer: it’s probably already on, it costs nothing, and it’s worth using for the right things. Here’s how it works, where it helps, and where it’ll bite you.

What it is

Plus addressing lets you add a tag to your email address on the fly. If your address is jane@yourcompany.com, then jane+acme@yourcompany.com, jane+webinars@yourcompany.com and jane+anything@yourcompany.com all land in Jane’s inbox. You don’t create anything ahead of time. You just make up the tag when you need it.

Gmail has supported this for years. Microsoft 365 turned it on by default for Exchange Online in 2022, so if you’re on Microsoft 365 and nobody has switched it off, you can start using it today.

Why it’s useful

The best reason is tracing. Sign up for a trade show as jane+phillybuildexpo@yourcompany.com, and if spam starts showing up at that address six months later, you know exactly who sold or leaked your contact info. That’s information you can act on: unsubscribe, block, or stop doing business with them.

It’s also a quiet phishing filter. If you gave your bank jane+bank@yourcompany.com and an “urgent account notice” arrives at your plain address, that’s a red flag before you’ve even read it. Attackers buy lists of base addresses. They rarely know which tagged version you gave which vendor.

Then there’s sorting. Give every vendor that sends invoices jane+ap@yourcompany.com and one Outlook rule drops every bill into the same folder. Same idea for newsletters, SaaS notifications and trial accounts, which keeps the clutter out of the inbox where real client email lives.

Where it falls short

It isn’t privacy. Your real address is sitting right there in front of the plus sign, and anyone who wants it can strip the tag off. Plenty of spam lists do exactly that. If you need an address that can’t be traced back to you, use a real alias or a forwarding service like Apple’s Hide My Email instead.

Some websites won’t accept it. A surprising number of sign-up forms still reject the + character as invalid. You’ll hit this every so often and just have to use your normal address.

In Microsoft 365 it’s receive-only. You can get mail at jane+acme, but you can’t send from it. When you reply to that vendor, your reply comes from jane@yourcompany.com. That’s usually fine, but it can confuse support portals and ticketing systems that match tickets by sender address.

You have to remember which tag you used. If you signed up for a vendor portal as jane+acme, that’s your login. Forget the tag and you’re locked out, and a password reset sent to jane@ won’t match the account. A password manager solves this, since it saves the exact username you used.

And don’t use it for anything critical. Your bank, payroll, your domain registrar and your Microsoft or Google admin accounts should all use your plain address. You want those logins boring and predictable, especially when you’re recovering an account under pressure.

So is it worth it?

Yes, with a simple rule: use tags for anything you’d sign up for and might regret later, and use your plain address for anything you’d need to recover in an emergency. Vendor sign-ups, webinars, newsletters, free trials and conference badges are perfect candidates. Banking, payroll, admin accounts and anything you need to send mail from aren’t.

Pick a naming convention and stick to it. Tagging with the company name (jane+acme) is the easiest to remember and the most useful when you’re trying to trace a leak.

Setting it up in Microsoft 365

If you’re on Gmail or Google Workspace, plus addressing already works. On Microsoft 365 it’s on by default, but some admins switched it off back in 2022 when Microsoft flipped it on for everyone. Here’s how to check it and put it to work.

Step 1: Make sure it’s on

Send yourself a test at you+test@yourcompany.com. If it lands in your inbox, you’re set. If it bounces, your admin needs to turn it back on:

1. Sign in to the Exchange admin center at admin.exchange.microsoft.com.
2. Go to Settings, then Mail flow.
3. Clear the box labeled “Turn off plus addressing for your organization.”
4. Click Save, give it up to an hour, and send the test again.

Step 2: Build a sorting rule

This is where plus addressing earns its keep. The example below files every bill sent to you+ap into a Vendor Invoices folder. Use Outlook on the web or the new Outlook, since rules made there run on Microsoft’s servers and keep working even when your laptop is closed.

1. Click the gear icon, then Mail, then Rules.
2. Click Add new rule and name it something like “Vendor invoices.”
3. Under Add a condition, choose “Recipient address includes” and type +ap.
4. Under Add an action, choose “Move to” and pick or create your Vendor Invoices folder.
5. Check “Stop processing more rules” so the message doesn’t get caught by anything else, then Save.

In classic Outlook for Windows, the same rule lives under Home, Rules, Manage Rules & Alerts, New Rule. Pick “Apply rule on messages I receive,” then the condition “with specific words in the recipient’s address,” enter +ap, and set the action to move it to your folder.

Now give every vendor that bills you the you+ap address. As they update their records, invoices stop landing in your inbox and start landing where your bookkeeper can find them.

Step 3: Shut down a leaked tag

When junk starts showing up at a tagged address, you’ve found your leak. Build a rule the same way, with “Recipient address includes” set to that tag (for example +phillybuildexpo), and set the action to Delete or Move to Junk Email. One rule and that source is gone for good, as long as the spammer kept your tag intact. If they stripped it, you’ll still know who sold your address, and that’s worth knowing.

If you’re an Open Tier client and want us to check your tenant or set up a few inbox rules to go with it, just open a ticket.