Sporadically when forwarding/replying to an email we get "Cannot Send Mail An error occurred while delivering this message" We have turned off "Undo Send" and the problem still occurs. The problem started at IOS 15.7 and continues to 16.2
I opened a ticket with our HCL Email Vendor. They reviewed the logs of the devices with this error on the server.
This is HCL's response:
"IOS Mail app randomly providing a policy key 0
To be technically accurate, we are talking about the following policy key that flows in the http request header
X-MS-PolicyKey: 0
The 0 is unexpected and will force Traveler to return a 449 so that the client and server will negotiate a new policy key. Typically its going to have a value like the following:
X-MS-PolicyKey: 369126834
That value comes from Traveler in response to an Exchange ActiveSync "Provision" command.
Example response payload:
<Provision xmlns="Provision:">
<Status>1</Status>
<Policies>
<Policy>
<PolicyType>MS-EAS-Provisioning-WBXML</PolicyType>
<Status>1</Status>
<PolicyKey>369126834</PolicyKey>
</Policy>
</Policies>
</Provision>
So something is happening with the iOS Mail app such that it is losing the current policy key. Its not possible to see what is triggering this from the traveler server. Its possible that the client is seeing some error (network?) for which it then gives up and starts with a policy key 0. That is pure speculation and something Apple support will need to comment on. When communicating with apple, use the header term X-MS-PolicyKey. Hopefully they recognize what we are talking about."
I've worked with Apple Tier 2 support and they aren't aware of the issue. I don't know how to get the right help on this. I've tried to open a Developer Ticket.