I don't think its an unreasonable rant being made by the OP - you've got a bunch of tasks, none of which you've looked at and some "e-mail forwarder" is asking you for estimates on time... screw that.
Where I work developers are in teams run by product managers (normally senior business analysts) each team/product manager looks after a different module. The time is scheduled for the developers often based on priorities set by account management (major factors in this are how much money the client is worth to us & how much of a fuss are they kicking up at the moment). If a project manager wants an estimate on time etc.. then it is up to him to speak to the product manager for whichever team he requires a fix/enhancement from & not go direct to the developers. The product manager has the clout to tell the PM to jog on if required.
Development time is valuable and needs to be devoted to the most important tasks, the priorities of which get decided at a strategic level. Every PM thinks that the project that he is responsible is important when quite frankly there are often higher priority items out there. I don't think that PMs should be allowed to pester individual developers and neither should developers have to predict time frames for stuff they've not even looked at yet & which may well have not have much in the way of a spec etc..
