B2C Password Reset Email issues with Cox.Net customers

Question

We are seeing a very high volume of customers using Cox.Net email address that either do not receive their password reset emails from B2C or see a long delay and by the time they do receive it the reset passcode has expired.

We do not have this issue with other email providers / domains. Seems to be something Cox is doing intentionally, wanted to see if others had seen this as well and if so how/if they were able to get it resolved.

Answer 1

We finally resolved this issue, posting details to hopefully save others the pain of getting this resolved in the future should they run into it.

Per Microsoft support:

• Our support team took the delayed email headers from last week and used those to look through our backend telemetry to map those specific emails and timestamps.
• They noticed an error code CXMXRT being thrown by COX in response to the email.
https://www.cox.com/residential/support/email-error-codes.html
• Our team then used the link above to match the error code, which says the email sender has exceeded the maximum number of sent email allowed.
• This morning our support engineering team and our service engineering team got on a call with COX engineering and showed them the issue, which has prompted them to increase the limit of emails being sent from Microsoft (through the password reset flow). This should allow these emails to flow through in the timely manner we would expect.

For those interested, here was the specific error code returned:

SEND20221216-7.LOG,2022-12-16T08:28:42.492Z,To_DefaultOpportunisticTLS,08DADDB8EE783F48,9,[2603:10b6:806:26f::20]:13027,[2a01:111:e400:7e8f::27]:25,<,452 4.1.0 ******@microsoftonline.com server temporarily unavailable. Refer to Error Codes section at https://www.cox.com/residential/support/email-error-codes.html for more information. AUP#CXMXRT