Signature Rules

Configure the application rules that control when and how email signatures are applied to outgoing messages. Rules determine which users receive which signature templates based on sender, recipient, and message conditions.

Note: Signature rules are implemented as Exchange transport rules (mail flow rules). They process messages server-side, ensuring signatures are applied regardless of email client.

Rule List

Rule Conditions

By Recipient Type

• External recipients only — Apply signature only when sending outside the organization
• Internal recipients only — Apply signature for internal communication
• All recipients — Apply signature to all outgoing email

By Sender

• Specific users — Apply to selected individual users
• Group membership — Apply to members of specific groups
• Department — Apply based on Azure AD department attribute
• All senders — Apply organization-wide

By Message Type

• New messages only — Apply only to original messages
• Replies and forwards — Apply to reply and forwarded messages
• All messages — Apply to all message types

By Domain

• Specific recipient domains — Apply when sending to specific domains
• Exclude partner domains — Skip signature for trusted partners
• Internal domains only — Apply only for messages to your own domains

Rule Priority

When multiple rules match a message, priority determines which template is applied:

• Lower priority number = higher precedence
• First matching rule applies (unless “stop processing” is disabled)
• Use priority to handle overlapping conditions (e.g., department + organization-wide)

Creating a Signature Rule

1. Name the rule — Provide a descriptive name explaining the rule purpose.
2. Select template — Choose which signature template to apply.
3. Set conditions — Define who and when the signature is applied.
4. Set exceptions — Exclude specific users or scenarios.
5. Set priority — Position the rule relative to other signature rules.
6. Enable — Activate the rule.

Best Practices

• Use specific conditions — Narrow rules to avoid applying wrong signatures.
• Set exceptions — Exclude automated system messages and service accounts.
• Test before enabling — Use test mode to verify rules match expected messages.
• Document rules — Describe the purpose of each rule for future administrators.

API Reference

GET /api/exchange/signatures/rules List signature application rules

POST /api/exchange/signatures/rules Create signature rule

PUT /api/exchange/signatures/rules/:id Update signature rule

PUT /api/exchange/signatures/rules/:id/priority Change rule priority

PUT /api/exchange/signatures/rules/:id/status Enable or disable rule