How do you set up a connector to relay mail through a third party Email Service Provider?

Hi @Ginny Lockwood

To relay emails from Exchange to ESP server, the general steps would be like:

1.add the recipient domain of the ESP server (for example contoso.com) as an accepted domain (external relay domain) in Exchange

For details please refer to this link: Accepted domains in Exchange Server

2.create a receive connector to receive emails from allowed ip addresses to be relayed

For details please refer to this link: Allow anonymous relay on Exchange servers

(It is suggested to only add the allowed ip addresses to the Remote IP addresses to avoid your Exchange server becoming an open relay)

3.create a send connector to send the emails to ESP server

For how to create a send connector, please follow these steps:

1.access Exchange Admin Center(https://<exchange FQDN>/ecp) and locate mail flow>send connectors

2.create a new send connector named ESP and select Custom as type

3.select Route mail through smart hosts

add the ESP server's ip address or server name as smart host

4.select Basic authentication and Offer basic authentication only after starting TLS, enter the credentials for authentication

5.configure emails sent to which recipient domain would be sent to this ESP server (in the below example, emails sent to recipients in contoso.com would be sent to ESP server)

6.select Exchange server as the source server

7.finish creating the send connector

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