Northwestern IT's central internal SMTP relays are supported by collaboration services.   The relays are defined by the following Geo-LoadBalanced DNS hostnames:

          smtprelay.northwestern.edu               

          hostsmtp.northwestern.edu

Geo (or geographic) implies that devices on Chicago subnets will send to the Chicago smtprelay server and devices on Evanston subnets will send to the Evanston smtprelay server. Devices on Northwestern's network may use the internal SMTP relays to send email notifications and alerts to both internal and external recipients.

Configuration

All Northwestern subnets have been added to the datacenter firewalls to allow unauthenticated, port 25 connections.  Use of the internal relays is 'locked down' by an allow list of specific IPs and IP subnets.  If your sending device's IP is not on the allowed list, then your email will not route. Instead you'll receive an SMTP error similar to the following:

          421 4.3.2 Service not available

To resolve please submit a TDX ticket to collaboration services asking to add the sending device's IP to the smtprelay allow list.  To expedite your request, also provide the purpose and type of device (ie. multi-function printer, server or software) making the connection.

Recommendation: Sending Email addresses

While these relays can historically accept any configured sending address, its strongly recommended to configure the sending address using a supported Northwestern domain. Doing so will improve the reliability of your message notifications not going to the recipient's Outlook Junk Email folder or blocked by an external institution's email content filtering platform.  Some examples have been included below to help illustrate the scenario.

Also avoid typographical errors and erroneous domains.