How to Configure Postfix Relay with Microsoft Office365

A lot of customers are using hosted Office 365 for outbound email.  There are different ways to set this up but some customers have had success with this method.  It requires that you know or find the public ip address that your Eclipse server is coming from.  If you have issues with this setup you must call Microsoft or whomever supports your Office 365 solution.

  • Log on to the Office 365 Portal.
  • Select Domains. Highlight one of your domains and use the wizard to obtain your MX record. The MX record will look similar to Make a note of the MX record for later.
  • In the upper right, select Admin and then select Exchange from the drop down.
  • In the Exchange Admin Center, select Mail Flow > Connectors.
  • Create an inbound connector.
  • Give the connector a name (example: Eclipse relay).
  • Select On-Premises for the Connector Type.
  • Under Domains, add a single asterisk (*). This will allow sending to any domain. Don’t add anything else.
  • In the IP Addresses section, add the public ip your Eclipse server comes from
  • Leave all the other fields with their default values and select Save.
  • In the DNS for your domain, we suggest that you modify your SPF record to include the IP address. The finished string should look similar to this: v=spf1 ip4: ~all where is your public IP address. Skipping this step could cause email to be sent to recipients’ junk mail folders.

Once this is complete the Eclipse UNIX/Linux team can assist with editing what your eclipse server points to for outbound email (sendmail or postfix).