Hope some find this amusing and not annoying. Perhaps someone know how to approach this issue toward a resolution.
We have an in house commercial email system. Due to a re-organization, a number of our users are now required to use an o365 account, yet must still receive internal messages. To that end, I helped create internal account specific rules to forward all internal messages to the individual o365 accounts. We chose "flat forward" instead of "as attachment". This appeared to work fine and does, for most messages. However, our org often sends an email to thousands of users with in our system. These messages fail to forward, bounced by o365 as "header exceeds static size limit" or to that effect. I can see that there are individual messages sent out to each recipient, as expected, yet each is bounced. If I forward the same message, as an attachment, it is not rejected. The same flat forward, sent to non o365 systems, do not get rejected. The o365 team maintains this is to be expected as o365 has a limit on the number of recipients that can be addressed in a single email. 500. I believe. I maintain they "got a bug" as each email is addressed to only one specific person, and should be interpreted that way, regardless of how may persons were addressed in the original header. If that is the correct term. The message envelope shows as well below their size limit. Am I wrong? If not, what can I pull of a hat to prove it?
