Hi @isobelhoward,
There's currently no way for a record to know info about its surrounding records in the same table (see my product suggestion here for more info: https://community.airtable.com/t5/product-ideas/all-formula/idi-p/155436) and therefore something like a formula field to filter a view that could evaluate submission dates for given email field values across records in the same table is not currently possible.
The Airtable way of achieving this is through linked records, table hierarchies, and roll-up field aggregations.
The simpler, albeit less ideal, option is to group by email address and sort by submission time to have the latest submission appear at the top or bottom of a submitter group.
Hope that helps!
-Stephen
The key here is identifying which record is the most recent submission.
If your entries are created with a form, you could run an automation on form submission that sets a {Is Most Recent} checkbox for the new submission, and clears the checkbox for any other records with the same email address.
I wrote a detailed explanation in Kuovonne's Guide to Airtable.