My approach to email is best described as ‘one bucket fits all’. Countless addresses all forward to one Gmail account, which I attempt to keep at inbox zero with the use of a lot of filters. Some days it works, other days the definition of ‘zero’ would make a mathematician cry.
The problem with this firehose approach is that when checking email on a mobile client, or even if I’m offline for a while, there’s a lot of noise. Not spam, per se; I might read all these newsletters and group mails if I’ve got time, but when I’m in a rush, it adds a lot of overhead to my email-checking and gives me plenty of ‘new email’ alerts when said item is pretty low down the priority list.
Solution: Layer upon layer of forwards. This might not work for everyone, but setting up several different Gmail (or provider-of-your-choice) accounts that all forward to the bucket account gives you the luxury of information filtering. Use one address for the really important stuff, and make that inbox the one you check while away; everything else can wait.
Advantages: Less interruptions; any new email is bound to be important.
Disadvantages: You’ll run into problems syncing your bucket account with this ‘filter’ account; items you read while away won’t get marked as read, as it’s a different inbox, and you’ll need to CC yourself on sent items. There are possibly (probably) hacks to get around most of the technical issues, if you’re finding it problematic.
Changing stuff over to the new email address might also be a problem, and you might end up subscribed to newsletters and the like anyway; using it for new projects is one approach, ensuring a fresh and consistent start with a clearly identifiable information source you can check.
Extra layer of technological wizardry: Instead of using your @gmail addresses directly, use a hosting service to redirect addresses at your .com (or similar) domain. That way you can change which bucket the addresses go to, have several pointing at the same one, etc; all without anyone but you knowing.