Published 24 Jul 2020

Users of Microsoft 365 will soon get the benefit of a little-known feature called email subaddressing, which is documented in the RFC 5233 email standard but not implemented by many leading email servers.

What does the feature allow?

The new “plus addressing” feature will allow email users to create variants of their email address by adding text to the local portion of their email address.

For example, John Smith has the email address With the new feature, he will be able create several variants to give out to contacts and use when signing up for websites or services. For example, he could give the address when signing up for news digests, and then give the address when communicating with prospective customers. Incoming emails for both addresses will be delivered to John’s usual inbox.

So, how is this useful?

All emails end up at the same address, but the main benefits arise when you start filtering emails, so they are treated differently depending on which email subaddress they were sent to.

For example, let’s say you like to keep abreast of developments in your industry, so you are signed up to several industry news websites and receive periodical digests in your inbox. Unfortunately, these get combined with other emails, leading to a somewhat cluttered inbox. You could, of course, set up filters, but you would need to do this based on the sender’s email and repeat it for each website you sign up to.

By using an email sub-address, though, you could just set up a filter to store all emails to a certain subaddress (e.g. in a separate folder. This leaves your inbox uncluttered, and you still can catch up on the news whenever you have time. What’s more, if you sign up with a new website using the same email address, its communications will automatically be filtered.

In contrast, you could also use these custom addresses to highlight important emails that may warrant an expedited response. For example, by creating an email subaddress just for sales leads (e.g., you can create rules that may help bring emails to your attention more quickly. There no specific details about how the feature will work in Microsoft 365 yet, but it’s not inconceivable that users will be able to customise smartphone notifications based on the email subaddress and restrict them to just the more important emails.

Other benefits include the ability to monitor which companies are sharing your email address by using a different subaddress for each one. What’s more, if a particular email subaddress is exposed in a data breach, you can more easily “dispose” of it.

The new feature is scheduled for release in the third quarter, when all Microsoft 365 subscribers will be able to begin using it. If you have not yet embraced the benefits of Office 365, we at Pro-Networks can ensure you can have a pain-free transition with our Office IT support services, as well as handle the licensing and administration for you if needed.


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