Plus Addressing (dynamic instant aliases with a +) for Microsoft 365, Outlook.com and Gmail
To easily sort out my newsletters from my actual emails, I’ve created an alias for my Outlook.com which is myname-newsletters@outlook.com.
Unfortunately, every now and then I tend to get a lot of spam on this address even though I don’t use it for emailing myself. I can only assume that one of the newsletters I signed up with is selling addresses.
I thought about creating an alias for each newsletter I sign up with but this process is rather cumbersome and the amount of aliases I can create on Outlook.com is limited.
Is there another way to approach this?
Exchange Online (Microsoft 365), Outlook.com and also Gmail.com accounts allow you to dynamically create an unlimited amount of aliases based on an existing alias or email address without the need to register them first.
The trick here is to use a + symbol in your address. This method is also known as “subaddressing.”
How it works
In this case, your registered email alias is myname-newsletters@outlook.com.
When you for instance sign up for a newsletter from Microsoft, you can use the address myname-newsletters+microsoft@outlook.com.
To receive email notifications from Amazon, you can sign up with the address myname-newsletters+amazon@outlook.com.
Outlook.com will still deliver messages sent to these addresses to your mailbox even though you haven’t registered them as an alias. This is because it simply ignores the part behind the + symbol and only uses the first part to determine to which mailbox it should be delivered. So you can use this to create a unique address for any place you leave your email address.
The full email address will also remain visible so if you receive any unexpected emails, you can easily find out who leaked the address by looking at the address it was sent to or the message header.
The header of a message sent to a + alias in Outlook.com.
Use a single rule to move all the + aliases
You can still sort all these messages to a single Newsletters folder via a single rule:
Move messages to Newsletters if recipient address includes “myname-newsletters”
To create a rule in Outlook.com;
- Click on the Gear icon in the top right corner (left from your profile picture).
- At the bottom from the Settings pane, click on; View all Outlook settings.
- On the Settings page select: Mail-> Rules
- Click on; Add new rule
- Fill out the following conditions and actions;
- Rule name
Newsletters - Add a condition
Recipient address includes: myname-newsletters - Add an action
Move to: Newsletters
- Rule name
The contains condition allows you to create a single rule to move all + aliases.
Supported mail systems and website forms
Exchange Online (Microsoft 365), Outlook.com and Gmail support creating these “instant” or “disposable” aliases with a plus symbol without needing to register them first.
Currently, when using Exchange Online, your administrator first has to enable this feature via the following PowerShell command.
Set-OrganizationConfig -AllowPlusAddressInRecipients $true
Various other popular mail servers used by ISPs and other mail providers support this as well. In some cases, they use a hyphen (-) instead of a plus symbol as a separator. Check with your provider whether or not they support it and if so, which the separator should be used.
Yahoo only half support this. They allow you to create an additional “base name” for your mailbox for which you can register up to 500 disposable addresses with the hyphen as a separator. For more information see: Disposable addresses in Yahoo Mail.
Microsoft Exchange On-Premises, like Exchange 2016 and Exchange 2019, does not support these type of instant aliases. Each alias address should be registered with a mailbox before it is being used.
Some online forms where you can leave your email address may not recognize the + symbol as a valid character within an email address. In that case, you’d still have to register a separate alias first for that website if you want to track its usage of your address.
