Restricting Email Communication to One Domain in Google Workspace (Gmail)

Objective

Allow [e-mail] to send and receive emails only with the domain icicibank.com. Block all other inbound and outbound email communication.

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Steps to Configure in Google Admin Console

1. Login

• Go to https://admin.google.com

• Sign in with your super admin account.

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2. Open Gmail Settings

• Navigate to: Apps → Google Workspace → Gmail → Compliance

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INBOUND Restriction (Receiving emails)

3. Add a Routing Rule

• Scroll down to Routing section.

• Click “Configure” (or “Add Another” if rules already exist).

Name: Allow inbound only from icicibank.com ([e-mail])

Emails to affect:

• Choose Inbound, Internal - receiving, and Outbound (optional) if needed.

Envelope recipient:

• Specify → [e-mail]

Add Expression:

• If the sender’s domain is not → icicibank.com

Action:

• Reject the message.

• Add a custom rejection notice, e.g. "This mailbox only accepts messages from @icicibank.com."

Save the rule.

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OUTBOUND Restriction (Sending emails)

4. Create another rule under Outbound

• Go to: Apps → Google Workspace → Gmail → Compliance

• Scroll down to “Outbound” section and click “Configure”.

Name: Allow outbound only to icicibank.com ([e-mail])

Emails to affect:

• Choose Outbound and Internal - sending.

Envelope sender:

• Specify → [e-mail]

Add Expression:

• If the recipient’s domain is not → icicibank.com

Action:

• Reject the message.

• Add a rejection notice, e.g. "This mailbox is restricted to send only to @icicibank.com domain."

Save the rule.

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5. Verify & Test

• From [e-mail], send:

  • ✅ To [e-mail] → should succeed.

  • ❌ To [e-mail] → should be rejected.

• From an external account:

  • ✅ From [e-mail] → should arrive.

  • ❌ From [e-mail] → should be rejected with your custom message.

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Summary Table

Direction	Allowed Domain	Blocked	Affected User
Inbound	@icicibank.com	All others	[e-mail]
Outbound	@icicibank.com	All others	[e-mail]

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Notes & Best Practices

• These rules apply only to the specified user ([e-mail]).

• Be careful if multiple routing rules exist — Google Workspace processes them in order.

• Always save and test after changes.

• Consider documenting the setup for audit purposes.