Chapter 4 FortiOS Carrier : ­­­­Overview of FortiOS Carrier features : How FortiOS Carrier processes MMS messages : FortiOS Carrier and MMS content scanning : MM1 Content Scanning
  
MM1 Content Scanning
During MM1 content scanning a message is first transmitted from the sender, establishing a connection with the MMSC. FortiOS Carrier intercepts this connection and acts as the endpoint. FortiOS Carrier then establishes its own connection to the MMSC. Once connected, the client transmits its m-send.req HTTP post request to FortiOS Carrier which scans it according to the MMS protection profile settings. If the content is clean, the message is forwarded to the MMSC. The MMSC returns m‑send.conf HTTP response through FortiOS Carrier to the sender.
If FortiOS Carrier blocks the message (for example because a virus was found, see Figure 136), FortiOS Carrier resets the connection to the MMSC and sends m-send.conf HTTP response back to the sender. The response message can be customized using replacement messages. FortiOS Carrier then terminates the connection. Sending back an m-send.conf message prevents the sender from trying to send the message again.
Figure 136: MM1 MMS scanning of message sent by sender (blocking m.send.req messages)
FortiOS Carrier also sends m-send.rec notifications messages to the MMSC that are then forwarded to the sender to notify them of blocked messages.