I echo the High Priority need. I see Microsoft implemented DMARC for their domain. Please help us get necessary data for implementation on our domains. As Jonas says, others like gmail are, why not Office 365?
Keep the feedback coming. We appreciate continued details as to which option(s) would work best. The trick is balancing notifying users (who usually can’t take action, but certainly want to know when messages are delayed) vs. notifying the admins (who may or may not be able to take action but may not want such a quick notification — for example if they are responsible for a server that is down for planned maintenance or a DNS change which takes time to propagate). We would certainly like for this to be somewhat configurable in the future, but also are considering alternatives to the current 48 hours.
Yes, we have business needs to support subaddressing. Is it on the MS roadmap yet?
We also need this is very infrequently, probably once or twice a year, but when it is needed it has significant business impact and is therefore very important. We have had previous cases where 1000+ addresses were incorrectly updated by automated processes and needed to be updated as quickly as possible.