Service Disruption – Increase in Deferred, Block, or Bounce Messages with DNS Related Responses

Sendgrid Outgoing Mail Gateway Original incident notification from SendGrid
These maintenances affect outgoing email on the Zenith Media Canada Network of servers, all outgoing email unless configured by the client to do otherwise rely on the smart host gateway of SendGrid.

May 19, 18:36 PDT
Resolved - Our engineers have been monitoring the situation and it appears that Deferred, Block, and Bounce messages with `55x` or `5.1.8` DNS related responses have gradually decreased since our fix. Although the majority of this issue has been mitigated, some users may still see lingering effects while DNS changes continue to propagate. We apologize for any inconvenience this has caused you and thank you for your patience. If you have any questions, please reach out to our Support team at

May 19, 15:49 PDT
Monitoring - Starting around 1pm MT on Monday, May 18th, customers may have noticed an increase in Deferred, Block, or Bounce messages with `55x` DNS related responses. Our engineers have implemented a fix and are now monitoring. We apologize for any inconvenience this may have caused. Please reach out to our Support team at with any questions.

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Have an issue thats being affected by this maintenance? Open a Ticket and we can help you find a solution.

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