How to whitelist or block sender domains

Need to make sure your alias only accepts emails from specific companies or domains? Or want to block a noisy sender? Alias rules let you create an allowlist (whitelist) or blocklist for any alias in just a few clicks.

Note: Alias rules require a Maker plan or higher.

Allowlisting: accept only trusted domains

The most common use case is restricting an alias so it only processes emails from domains you trust. For example, if your invoices@yourcompany.com alias should only accept emails from your two suppliers:

Step-by-step

  1. Open the alias you want to protect
  2. Go to the Rules tab
  3. Click Add rule
  4. Set rule type to Allow
  5. Set criteria to Sender domain
  6. Enter your trusted domains: @supplier-one.com, @supplier-two.com
  7. Save the rule

That's it. Only emails from those domains will trigger your webhook. Everything else is silently rejected.

How the allowlist works

When you create one or more Allow rules:

  • Emails matching any allow rule are accepted
  • Emails matching no allow rule are rejected
  • If you also have block rules, those are checked first

This means you don't need to think about blocking — just define who's allowed and everything else is excluded automatically.

Blocklisting: reject specific domains

If you want to accept most emails but block a few noisy or unwanted senders:

  1. Open the alias
  2. Go to the Rules tab
  3. Click Add rule
  4. Set rule type to Block
  5. Set criteria to Sender domain
  6. Enter the domain(s) to block: @spam-company.com
  7. Save the rule

Combining domain and email filters

You can create multiple rules on the same alias. Common patterns:

Allow a company but block one person:

Rule 1 (Allow): Sender domain = @bigcorp.com
Rule 2 (Block): Sender email = noreply@bigcorp.com

Allow multiple partner domains:

Rule 1 (Allow): Sender domain = @partner-a.com, @partner-b.com, @partner-c.com

Block competitors from a shared inbox:

Rule 1 (Block): Sender domain = @competitor1.com, @competitor2.com

Notifying blocked senders

By default, blocked emails are silently rejected. If you want the sender to know their email was filtered, enable Notify sender when blocked on the rule. This sends them a short rejection notice.

Use notifications when:

  • Legitimate senders might accidentally be blocked
  • You want to signal that the alias is restricted

Skip notifications when:

  • Blocking spam or unwanted marketing
  • You don't want to confirm the alias is active

Tips

  • Use domain rules over individual email rules — they automatically cover new employees or shared addresses at that company
  • Start simple — one allow rule with your trusted domains is often all you need
  • Test first — send a test email from an allowed and a non-allowed address to verify the rule works
  • Combine with spam filtering — rules handle your specific allow/block needs while spam filtering catches general junk

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