As of October 28th, 2015, SoftLayer no longer allows outbound connections through TCP port 25 (SMTP) on new accounts.
Why is a standard email port blocked?
By default, the standard SMTP TCP port 25 is blocked due to the large amount of abuse this port is susceptible to. We offer a trusted third party email relay service from SendGrid for those customers who need to be able to send outbound email from their domains or applications.
What options do I have if I want to send email from my server or application?
Customers will need to employ the use of a Smart Host outside of the SoftLayer network to send email from their servers. A Smart Host is simply a relay host that relays SMTP traffic from an SMTP server, mail client, or any other service or programming language capable of handling SMTP. Servers typically send this type of traffic via the mail submission TCP ports 465 or 587. Customers can communicate with those or any custom port of their choosing only TCP port 25 is blocked. If you want to use your own email server on a custom port, use the documentation specific to your email service to configure a custom email port.
Does SoftLayer offer a Smart Host service?
SoftLayer now offers an Email Delivery Service powered by SendGrid that allows clients to utilize a SmartHost to relay their outbound mail services. This is not “just a relay.” The service also generates metrics, tracks email lists, tracks email activity (bounced, clicked, dropped, opened, etc), assists with newsletters, provides authentication, and much more.
Set up email services for use with your server.
Additional detailed usage and integration documentation can be found on this SendGrid Site.