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📨Mail Aliases: What & Why

📨Mail Aliases: What & Why

Mail aliases are alternate email addresses that deliver to the same mailbox.

 

They let you:

  • Filter & organize incoming mail

  • Track where sign-ups/newsletters come from

  • Protect your real address

  • Quickly disable an address by removing the alias

 

Alias methods vary by provider—below are some common tricks and platform specifics.

Gmail Tricks

1. “Plus” Subaddressing ➕

Gmail ignores anything between your username and the @.

  • Format: yourname+tag@gmail.com

  • Example:

    realname@gmail.com realname+shopping@gmail.com → goes to realname@gmail.com realname+work@gmail.com → goes to realname@gmail.com

  • Use Cases:

    • Newsletter sign-ups: you+newsletter@gmail.com

    • Automated filtering: label all you+shopping@… as “Shopping”

2. “Dot” Ignoring • • •

Gmail also ignores periods in the username part.

  • Any of these are equivalent:

    your.name@gmail.com y.ourn.ame@gmail.com yourname@gmail.com

  • Trick: Use different dot-patterns to test where spam or leaks originate.

Other Consumer-Level Aliasing

  • Fastmail & ProtonMail: support full subaddressing (+tag) and custom domains.

  • Catch-all Addresses: set up *@yourdomain.com to route everything to one mailbox (great for testing but beware of spam).

Enterprise Use Cases

Microsoft Exchange & Office 365

  • Proxy Addresses (Aliases):

    • You can assign up to 400 SMTP proxy addresses per mailbox (including the primary address).

    • Supports multiple domains (e.g., user@primary.com, user@aliasdomain.com).

  • How to Add an Alias (Exchange Admin Center):

    1. Open Exchange admin center → Recipients → Mailboxes.

    2. Select the user and click Email address.

    3. Click + Add email address, choose SMTP, and enter the new alias.

    4. Save changes.

  • Office 365 (Microsoft 365) Portal:

    1. Go to Users → Active users.

    2. Select user → Manage username and email.

    3. Under Aliases, click Add alias, enter it, then Save.

  • Distribution Groups & Shared Mailboxes:

    • Use when you need multiple people to receive mail to a single address (e.g., support@, sales@).

    • Shared mailbox quotas and permissions managed separately from user mailboxes.

Other Enterprise Platforms

Platform

Alias Limit

Notes

Platform

Alias Limit

Notes

Google Workspace

essentially unlimited + subaddresses¹

No GUI for SMTP proxies; use plus addresses or domain aliases

Office 365

400 proxy SMTP

GUI and PowerShell support for bulk operations

Zimbra

unlimited

Supports both alias and forwarding rules

Postfix (self-host)

unlimited

Configure virtual_alias_maps in main.cf

Best Practices & Tips ✅

  1. Use consistent tags

    • e.g., user+clientA@…, user+clientB@…

  2. Automate filtering

    • In Gmail/Workspace, create filters based on +tag → auto-label/archive.

  3. Monitor alias usage

    • If an alias starts receiving spam, you can disable it or add it to a blocklist.

  4. Document aliases in your KB

    • Keep a table of active aliases and their purpose, especially in larger orgs.

¹ Plus-addressing in Workspace can’t be disabled and works across all Google services.