Looks like a valid request. Would you be willing to provide a patch?

From http://msdn.microsoft.com/en-us/library/ee219609%28v=EXCHG.80%29.aspx it seems that 'All' is not a valid value for this header. Would 'OOF' be a valid reply value or should I add something else, like 'AutoReply'?

in your link, i understand that 'All' is valid... but you can choose which types of auto-responses you want to suppress or not in the case the value is not 0 (none) or -1 (all)

(cannot submit patch easily, proxy at my office doesn't allow connections to Git)

You're right, I misread that link. This is now fixed.

thanks for the patch (now github is blocked too by the proxy at office :@ i'm trying to allow github and the protocol git to be used but not very simple...)

Marking as 'acknowledged' not resolved/closed to track that change gets ported to master-2.0.x branch