SMTP Relay Services (Simple)

Updated by Erik Jensen on Nov 28, 2016

IMPORTANT NOTE: The SMTP Relay Service is being End of Serviced on December 1, 2016 with an End Of Life on January 15, 2017. Please refer to our SMTP Retirement FAQ for more information. Please refer to our SMTP Retirement FAQ for more information.

SMTP Relay can be used to do application level email relay without the need of managing your own SMTP server/service. The current offering is prices at $0.10 per 1000 emails sent via the service and billed at the account level.

You can sign up for the service easily by going to the Contol Portal > Services > SMTP Relay. From here you can create an SMTP relay account by doing the following:

  • Click the "Create SMTP Relay" button.

  • It will create a user to be used on the service and will be listed with an alias, password, status such as:SMTP Relay Users List

  • Now you can connect to the SMTP relay service from your virtual servers at CenturyLink Cloud.

Connect to the SMTP Relay Service

Connecting to the SMTP service is very easy as it is done via port 25 from inside the CenturyLink Cloud. Here are the settings:

  • SMTP Host:
  • SMTP Host Port: 25
  • User: (what is provided in your control portal as the alias)
  • Password: (what is provided in your control portal)

You will also need to add SPF record as follows: v=spf1 ip4:

API's for SMTP Relay Provisioning:

Here are the links to the provisioning service for the SMTP Relay that can be used to manage SMTP relay accounts and get invalid addresses such as bounce backs:

RHEL Compatible Postfix Basic Setup

Install pre-reqs:

> sudo yum install cyrus-sasl{,-plain}

As root create the file /etc/postfix/smtp_sasl_password_maps with the following content (substituting your alias and password) $alias:$password

Create a hash of your password map:

> sudo postmap /etc/postfix/smtp_sasl_password_maps

Add the following lines to your /etc/postfix/

smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/smtp_sasl_password_maps
smtp_sasl_security_options = noanonymous
relayhost =

Reload postfix and test

> sudo /sbin/service postfix reload

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