This is not about ignoring tags in the search but in the individual filters one can subscribe to via email. (Link: Form to create such a filter)
To include only questions with a certain tag in the filter is pretty straight forward. Just add them with "Just questions tagged with the".
When several tags are in the list, they are connected with
But is there a way to exclude questions, which do have one (or more) of the tags listed but also another one I want to ignore?
Similar to the search
[ruby] [testing] -[ruby-on-rails*], which selects all questions tagged with
[testing] excluding those questions which are as well tagged with one of the
[ruby-on-rails] tags (including
If there is such a functionality not yet implemented, it would be very nice having one.