> ## Documentation Index > Fetch the complete documentation index at: https://docs.vouch.expert/llms.txt > Use this file to discover all available pages before exploring further. # Alias Detection > Detect plus-addressing and email aliases ## Overview Alias detection identifies plus-addressing (also called subaddressing), where users add a tag to their email address like `user+tag@example.com`. This allows one email address to create unlimited variations. Typically configured as **FLAG** since aliases can indicate multi-accounting but are also used legitimately. ## What is Plus-Addressing? Plus-addressing allows users to add a tag after a `+` symbol: ``` user@example.com # Base email user+shopping@example.com # Shopping alias user+newsletter@example.com # Newsletter alias ``` All these deliver to the same inbox: `user@example.com` ## Why It Matters * **Multi-accounting**: Users can bypass "one account per email" limits * **Trial abuse**: Create unlimited free trial accounts * **Referral fraud**: Exploit referral programs ## API Response ```json theme={null} { "checks": { "alias": { "pass": false, "latency": 0.3 } }, "signals": ["alias_pattern"] } ``` `false` if plus-addressing detected, `true` if not Check execution time in milliseconds ## Configuration Recommended to FLAG aliases since they can be legitimate but may indicate abuse. ## Next Steps Track multi-account abuse Block temporary emails