Re: Mail.app DoS/BAD parse error: invalid message sequence number

["David N. Blank-Edelman" <dnb@ccs.neu.edu>]

Hi Thom-
  Thanks for such a thoughtful reply. I appreciate the care that is taken when considering changes like those we are talking about. The one thing I do need to point out is for us, the following is not true:

> As Xueshan and Zimbra Engineering have noted, we do not believe at this time that the BAD parse problem increases load significantly or has other significant performance or functional impact on the server other than increasing the mailbox.log size.

We see very significant performance degradation when a single client on gig-E gets into this tight loop with our server and spits tens of requests per second at it. Degradation to the point where other users complain about UI slowness in the web client among other things. 

I don't know whether our setup is lower latency/less distributed than others or just poorly sized/tuned from our original planning with the sales engineer lo those many moons ago when we first put this into place. We do wind up with this manifesting as a more serious problem than log space usage. I wouldn't be advocating for more rapid response than just waiting for Apple to fix their client  if we didn't find this bug to be a real hazard. But I'm more than willing to believe the problem for us is exacerbated by how our server is provisioned.

We'll be upgrading our original setup in the next few months using considerably beefier hardware. The quote is actually going to go in tomorrow or Monday. Perhaps that will provide enough horsepower so this turns into just noise when it happens, I  was just hoping to not have to wait and see.

    -- dNb

P.S. One other fleeting thought that came to mind that may not cause the Engineering team to gnash their teeth would be the idea of more judicious logging (i.e. aggregate certain messages or messages at a certain rate) in cases like this. It is a bit late here so I can't really tell how good an idea that might be.