A contact or multiple contacts that are using a certain domain are not able to submit incidents. How can I identify the cause of this issue?
If a contact that is using a certain domain, e.g @example.com, is not able to submit incidents, the first thing that you need to do is to check if the domain is blocklisted due to bad reputation.
In order to check if a domain is blocked, check Cisco's IP & Domain Reputation Center.
If the domain is listed, the owner of the domain must contact Cisco's Reputation Center Support team via email and request a review of the domain's reputation. Note, the reputation is also based on the domain's appearance on other notable block lists so it may be necessary to contact block list owners individually to inquire about potential removal (ex. Spamhaus SBL, SORBs, etc..).
If the domain is not listed, you can use the standard report ID 227 "Incoming Email Filter Details". This report displays details concerning incoming email messages that were filtered.
If you are still not able to find the cause of this issue, using above options, submit a service request to Ask Technical Support and our Technical Support team will investigate the matter further.
For more information on blocklists, refer to Answer ID 9014: Blocklists and Removal Handling.