Filter by another two variables that accompany the email table (ex: profile) that also accompany other tables. Essentially, these filters are more like global filters. This enables the ability to create an app for one larger group/community which hosts smaller groups/communities.
For example, an alumni directory for a university with multiple schools (e.g. engineering, liberal arts, etc) where users they can only see others profiles from the same year and same school. For instance, they could have a Profile, Alumni List, & Faculty List. When they login they can see a table their profile, a list of alumni their year in their school (who each have a school & year ID), and a list of faculty from their school.
This will be amazingly helpful from a perspective of data management and also creates many more use cases.
You could possibly set up a profile sheet. When a user signs in, they can fill in the profile sheet with details like name, school and year. Then have a School sheet that contains each school and year combination. Using a template column, join the school and year into one column to use as a key column in the School sheet. Also create a similar template on the Profile sheet. Now create a multiple relation column in the School sheet to link the template column in the School sheet to the template column in the Profile sheet. Next create a Lookup column in the School sheet that will use the relation you created to pull back an array list of emails for each Student that belongs to that school and year. Now on the tab for the School sheet, change to detail style layout, apply filter by signed in user, which will use the lookup column and only show the school and year that the user belongs to. Add an inline list to that detail view, which will use the relation to show all of the students that belong to that school and year.
For faculty, you can either use the same school year relation and create a record for each faculty member for each year they are in that school, or create a new relation that will only use school to link to the profile sheet school. Then you can create a separate inline list to show the faculty on the school details page.