Should I be able to see outbound emails? Currently, I can only see inbound.
If you use an internal mail server e.g. Exchange for sending e-mails -> you have to config the Sophos UTM internal IP as smarthost there and you have to allow host based relay on the Sophos UTM for your mail server / exchange host. Than you´ll see inbound and outbound mails using Sophos Mail Manager.
We're currently using a Hybrid set-up and mail from 365 to On-Prem turns up in our Mail Manager but tenant to tenant does not which I find very strange. Is there a reason for this?....Sorry to jump in on this thread... :)
Yes, of course! It worked as designed, mails between tenants/ exchange online users will always routed directly between exchange online servers
Why? Its easy:
source and targed mailservers are the tenants exchange onlineserver, so why an extra step between it with onpremise? Its the wrong way, if a mail from exchange online server will go trough on premise and than again back to the targed exchange online server.
so, this mails go never trough on premise.
example: in hybrid envoirment, if 2 O365 mailboxuser of same tenant write each other, it will not go trough onpremise exchange.
So can I ask what kind of protection does EOP use for Mail security?
Exchange Online Protection (EOP) overview - Office 365 | Microsoft Docs