Lately I've noticed that hovering over tags opens a mini info-window with tag related data and activities including email subscription option. Great!
But instead of subscribing to just a single tag I'd rather subscribe to a combination:
tagX and tagY and tagZ ...
giving me a much better selection of questions delivered to my email inbox.
Similar to viewing questions with a particular tag. You can always click on any of the related tags and you get a subset of questions that have both tags (the first one and the second one as well) and not either.
Is this kind of email subscription possible or are there any plans on developing it?
Tag sets on StackExchange (as suggested by @Barry) don't work, because they are combined by an OR operator instead of an AND. A tag set therefore widens the filter instead of narrowing it. Just so you know this question hasn't been sufficiently answered yet.