This task blocks T167085.

This task depends on T151161#3552414 (Bitergia to update the currently outdated list of latest new Gerrit authors).
This issue cannot be worked around (as I do not see any API to query by date && first activity and MZ's Gerrit-reports does not sort / display dates ).

This task also depends on having a recent DB dump of wikimedia.biterg.io (either manually updated, or by fixing T157898). Then I can query corresponding email addresses for Gerrit user names via a script (SELECT email FROM identities WHERE source='gerrit' AND username = 'SomeGerritUsername';).
This issue could be worked around by going to https://gerrit.wikimedia.org/ and using the Search field, entering author:SomeGerritUsername and waiting for autocomplete to trigger and show the author's email address.
Which needs to be done one by one and will take way longer.

(Irrelevant, just for my own notes: I thought the latter issue could also be worked around by using admin access on wikimedia.biterg.io to look up email addresses for each Gerrit username (going to the "Discover" mode, making sure in the left pane dropdown that you're in the "gerrit" index, entering author_user_name="SomeGerritUsername" in the text search field at the top, and expanding an entry) but I just realized that these entries do not offer the user's email address in Gerrit for reasons I do not know.)