To successfully configure your mail server, connectors, transport rules, and a correct MX record are required.

Option A: Exchange Online (Microsoft 365)

1. Set Up Connectors

Connectors control the mail flow between your Microsoft 365 organization and Conbool. Two connectors are required.

Navigation: Microsoft 365 Admin Center → Exchange Admin Center → Mail flow → Connectors

Outbound Connector (To Conbool)

Routes emails from your organization through Conbool.

1. Click + Add a connector.
2. Connection from: Office 365
3. Connection to: Partner organization
4. Name: e.g. Conbool Outbound Connector
5. Connector type: OnPremises
6. Smart Hosts: mail.conbool.com
7. TLS settings:
   • TLS settings: DomainValidation
   • TLS domain: mail.conbool.com
8. Use MX Record: No
9. Is Transport Rule Scoped: Yes
10. Enabled: Yes
11. Review summary → Create connector.

Inbound Connector (From Conbool)

Allows Conbool to deliver emails to your organization.

1. Click + Add a connector.
2. Connection from: Partner organization
3. Connection to: Office 365
4. Name: e.g. Conbool Inbound Connector
5. Connector type: OnPremises
6. Sender Domains: * (all domains)
7. Require TLS: Yes
8. TLS Sender Certificate Name: mail.conbool.com
9. Restrict Domains to Certificate: Yes
10. Enabled: Yes
11. Review summary → Create connector.

2. Define Transport Rules

Transport rules control which messages are routed through Conbool and prevent loops.

Navigation: Exchange Admin Center → Mail flow → Rules

Rule "Relay to Conbool"

Determines which emails are routed through Conbool.

1. Click + Add a rule → Create a new rule.
2. Name: e.g. Conbool Exchange transport rule
3. Sender address location: Header or envelope
4. Apply this rule if…
   • The sender is located… → Inside the organization
5. Do the following…
   • Route the message to the following connector → the outbound connector created earlier (e.g. Conbool Outbound Connector)
6. Except if… (add all of the following exceptions):
   • A message header matches → Header: X-Conbool-<YourDomain> (e.g. X-Conbool-example-com) → Pattern: true
   • The message type is → Calendaring
   • A message header contains → Header: Return-Path → Words: <>
   • The sender address matches → Pattern: <>
7. Priority: 0
8. Mode: Enforce
9. Save and Enable.

Rule "Classify Spam"

Automatically classifies emails marked as spam by Conbool.

1. Click + Add a rule → Create a new rule again.
2. Name: e.g. Conbool Spam classification rule
3. Apply this rule if…
   • A message header matches → Header: X-Conbool-Flag → Pattern: YES
4. Do the following…
   • Modify the message properties → Set the spam confidence level (SCL) → 7
5. Priority: 1
6. Mode: Enforce
7. Save and Enable.

Option B: Exchange On-Premises

1. Set Up Send Connector (Outbound to Conbool)

A Send Connector routes outbound emails through Conbool.

Navigation: Exchange Admin Center (On-Premises) → Mail flow → Send Connectors

1. Create a new Send Connector.
2. Name: e.g. Conbool Outbound Connector
3. Type: Custom
4. Address space: * (all domains) or specific domains as needed
5. Smart host: mail.conbool.com
6. Smart host authentication: None (authentication is handled via TLS certificate)
7. TLS settings:
   • Enable Require TLS
   • Domain validation: mail.conbool.com
8. Use MX Record: No
9. Source server: Select the Hub Transport server(s) that should use this connector.
10. Create and enable the connector.

2. Set Up Receive Connector (Inbound from Conbool)

A Receive Connector allows Conbool to deliver emails to your Exchange server.

Navigation: Exchange Admin Center (On-Premises) → Mail flow → Receive Connectors (on the respective server)

1. Create a new Receive Connector.
2. Name: e.g. Conbool Inbound Connector
3. Type: Partner
4. Network adapter bindings: Leave default (all available IPs, port 25)
5. Remote IP ranges: Enter the Conbool IP addresses (provided by Conbool).
6. TLS settings:
   • Enable Require TLS
   • TLS Sender Certificate Name: mail.conbool.com
   • Restrict Domains to Certificate: Yes
7. Create and enable the connector.

Firewall: Make sure port 25 (SMTP) is open from the Conbool IP addresses to your Exchange server.

3. Define Transport Rules

Transport rules ensure outbound emails are routed through Conbool and prevent loops.

Navigation: Exchange Admin Center (On-Premises) → Mail flow → Rules

Rule "Relay to Conbool"

1. Create a new rule.
2. Name: e.g. Conbool Exchange transport rule
3. Sender address location: Header or envelope
4. Apply this rule if…
   • The sender is located… → Inside the organization
5. Do the following…
   • Route the message to the following connector → the Send Connector created earlier (e.g. Conbool Outbound Connector)
6. Except if… (add all of the following exceptions):
   • A message header matches → Header: X-Conbool-<YourDomain> (e.g. X-Conbool-example-com) → Pattern: true
   • The message type is → Calendaring
   • A message header contains → Header: Return-Path → Words: <>
   • The sender address matches → Pattern: <>
7. Priority: 0
8. Mode: Enforce
9. Save and Enable.

Rule "Classify Spam"

1. Create a new rule.
2. Name: e.g. Conbool Spam classification rule
3. Apply this rule if…
   • A message header matches → Header: X-Conbool-Flag → Pattern: YES
4. Do the following…
   • Modify the message properties → Set the spam confidence level (SCL) → 7
5. Priority: 1
6. Mode: Enforce
7. Save and Enable.