out of office messages not being delivered to external senders

[Greg.Howley]

A bit of an odd situation.

We are migrating to a cloud email provider.

For our early test users, email from external users comes to our ironports, flows through to exchange, then exchange forwards it out (through ironport again) to a shadow domain that is accepted at the cloud provider.

If one of our test users turns on their Out of Office at the cloud provider, nobody received any OOO auto message.

I turned off bounce tagging to the shadow domain.  Now the users exchange account gets an OOO auto-reply, but the original external sender still gets nothing.

Any ideas on how to fix this?

[Libin Varghese]

Greg,

From what I understood currently the mail flows as below

Internet -> ESA -> Exchange -> ESA -> Cloud Server

I think we would need to determine how the exchange is forwarding these emails to the ESA, if the mail from and rcpt to address changes then the out of office coming back would be processed accordingly.

If the email was modified in order for it to be sent back to the ESA and out to the cloud, I would expect the out of office email reaching the exchange should be modified and sent to the ESA in order for it to go out to the internet.

OOO from cloud -> ESA -> Exchange -> ESA -> Internet

Following the out of office email and reviewing the mail-from, rcpt to should tell us why the email did not get processed beyond that point.

Thanks
Libin