Based on my testing yesterday our SMTP inbound server is not affected by this, we properly separate out the end of messages in all the demonstrated cases inside the report. It's kind of against RFC but it protected us from having the issue. We interpret all different iterations of <CRLF>.<CRLF>, including ignoring special null characters. This causes each message to be treated individually.

I'm going to be doing some additional checks to make sure our outbound SMTP server isn't affected some how by messages sent internally bypassing the SMTP server (messages from webmail) but we are not affected by the main issue with the inbound SMTP server not understanding message separations and all the different forms it can appear.