Subaddressing
Adding a tag to the local part of an address, usually after a plus sign (ana+news@example.com), so mail reaches the same mailbox but can be sorted by tag.
What it means
RFC 5233 describes the convention for Sieve filtering: a local part split into a user and a detail by a separator, commonly +. The receiving system delivers ana+news@example.com to ana@example.com and keeps the detail available for rules. Gmail supports it, and Microsoft enables plus addressing by default in Exchange Online; whether any other domain does depends on its mail system.
People use plus addresses to sort mail and to see which sender passed their address on. For senders, two addresses that look different may be one person, and a form that rejects + as invalid turns away real users; the syntax is valid under RFC 5322.
Example
ana+newsletter@example.comRelated terms
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 5233: Sieve Email Filtering: Subaddress Extensionrfc-editor.org
- Google Workspace Learning Center: Tips to optimize your Gmail inboxsupport.google.com
- Microsoft Learn: Plus addressing in Exchange Onlinelearn.microsoft.com
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