High delay rates with "internal" error

Incident Report for SparkPost

Resolved

We identified and resolved an outbound connection issue that appears to have mostly been affecting yahoo.com and hotmail.com. We have implemented a fix and will be adding additional monitoring to alert us if a similar issue happens in the future.

Posted Sep 20, 2016 - 14:46 EDT

Investigating

There are a high number of delays with these reasons:
451 4.4.1 [internal] No valid hosts (too many connection failures)
451 4.4.2 [internal] no HELO/EHLO response
454 4.4.4 [internal] no MX or A for domain
421 4.4.0 [internal] no MXs for this domain could be reached at this time
451 4.4.1 [internal] No valid hosts (unable to make any connections)

Any mail that has been queued will be delivered once we resolve this issue.

Posted Sep 20, 2016 - 13:25 EDT

This incident affected: SMTP Delivery (Outbound Message Delivery) (SMTP Delivery - USA).