The Setup Database / Data Rention Option: "Do not delete message content of incomplete messages" should be CHECKED by Default AND another Option "RETRY INCOMPLETE MESSAGES" should be added and Also CHECKED by default.

There appears to be a bug in 2.0.7 and 2.0.8 that is prematurely disconnecting email delivery to our inside email server for specific emails. The killer was that the default behavior of SG 2.0.7 and 2.0.8 is to delete the emails when it cannot complete delivery to the inside domains. There should also be a RETRY mechanism for this.
I do not know if this was a problem with earlier SG versions.

In my case, the problem was undetected until after 4 days of testing and 2 days in production the SG appeared to be working excellently with thousands of emails are being processed by the SG. I didn't discover the problem that less than 1% of the emails were being dropped with Result Incomplete and for some specific customer's application ALL of their emails are disconnected and deleted.

I think the Data Retention option resolves the Deletion of Incomplete emails issue.

However, I have to take the SG off-line and use our previous email methods until the connection dropping for specific email (compatibility issue?) is solved so 100% valid emails can be processed reliably by SG; and RETRY INCOMPLETE EMAILS option(s) are added to the SG. I bought 2 years subscription, so I really hope we get this issue resolved - and soon..