SocketLabs, Suppression Lists

If an email fails to send to a particular address many times in a row, SocketLabs will add the email to a suppression list to prevent further emails from being sent to a dead email. The IT Service Desk will need to remove the address from a suppression list manually to allow emails to be sent like normal once again.

How Accounts Land on Suppression Lists

The Suppression List feature of SocketLabs is designed to prevent emails from being sent to invalid or inaccessible email addresses. If an attempted email delivery returns a Permanent Negative Completion code, then SocketLabs will add the recipient address to the suppression list.

Most often, this happens when someone makes an effort to contact the University of Illinois before their Illinois email address is active.

For example, when an incoming student or new employee claims their NetID, there is a period of time before their Exchange mailbox is created where email forwarding will still function through the Electronic Directory Editor (EDE), and the TeamDynamix ticketing application (TDX) will have already created a user profile for them. If they then submit a ticket through TDX, the auto-reply will attempt to be delivered to an Exchange mailbox that doesn't exist yet. When this happens, the SMTP return code is 5XX, and SocketLabs will permanently add their email address to a suppression list.

What Happens to Accounts on a Suppression Lists

Many applications on campus use SocketLabs for email delivery and delivery metrics. The suppression list feature is designed to prevent mail from being sent to dead or boucning email addresses. Email delivery will not be attempted to any email addresses that are on a suppression list.

Suppression lists are managed on an application-by-application basis; there is no global suppression list for all services on campus. For example, if an email address is added to a suppression list for TDX, it will only affect TDX email delivery. Any other services using SocketLabs will still attempt to deliver emails to the address until added to their own suppression list.

How to Remove Accounts From Suppression Lists

Once added to a suppression list, email addresses are never automatically removed.

The IT Service Desk will be able to search through all available suppression lists in SocketLabs to see if an email address is present, and remove them from a list if found.

If you suspect that your email address has been added to a suppression list, please contact the Technology Services IT Service Desk by submitting a ticket or emailing consult@illinois.edu.



Keywords:
socketlabs socket labs supresion suppresion supression can't receive tdx emails no email from 
Doc ID:
47633
Owned by:
Help Desk Technology Services G. in University of Illinois Technology Services
Created:
2015-02-26
Updated:
2026-07-17
Sites:
University of Illinois Technology Services