Cognos scheduled Report Views not sending to a specific DL after error

[VicEh]

I have a report view that was working until a specific date when there was error as per the attached.

The report view sends to 3 DLs (distribution lists) and 1 individual. Ever since the error occurred, only 2 DLs and 1 individual get the report. Also, ever since the error occurred, no matter which report I add the DL that is the issue to, it won't send to that specific DL.

Any insights would be appreciated. Our IT team both on Exchange and Cognos side cannot figure it out. I'm thinking there is some sort of failsafe that catches problematic DLs and then blocks them for all future sends. All other DLs and emails are working perfectly fine, it's just the one DL (which worked before Oct 27).