Has anyone implemented PMG as a spam filtering front-end to an Office 365 domain? If so, what has been your experience?
I need information about this, need to configure outbound mail and we can only use the standard port 25. But port 25 are bound for inbound mail only.
Isn't Office 365 hosted and provided at/by Microsoft? Then you won't have a chance for outbound filtering. Inbound may be possible but also may break your active sync/autodiscover setup.
Interesting, however, you need to know, that a „good“ incoming filtering eliminates „sideattacks“, so my „real“ mail systems are only available via pmg and not directly any more as spammers may bypass your mx settings and try the host directly or may find office 365 records in your zone and try to deliver directly. That said, you only have three options: 1. open a bug to have a feature request adding the possibility to have multihomed (more IP addresses) environments and then set incoming filtering on one IP port 25 and outgoing filtering on another IP port 25 2. doing the above by yourself by adjusting the master.cf after copying from templates and have two IP addresses or alternative have two installations of PMG on two machines, one for outgoing, one for incoming 3. if you’re aware of the ip addresses, mails are coming from and you‘ve dedicated ip addresses at Office 365 setup a firewall which NAT IP address pool to port 26 internally, however, if you’re on shared environment, that won’t work as all other customers on the same infrastructure would be handled as outgoing by PMG when sending mails to you from the same IPs
Ok, but I have a rule for sideattacks. My Office365 only accepts mail from Proxmox. 1. Ok, I will. 2. Yes, I see the problem. Multihomed port will be an solution for that.
