I have set up a workflow that triggers when a field (user email) is modified in a module, and uses a custom function to get the user's name (from a different module, based on the email) and set that name into the name field in the original module. It works like a charm whenever an email is now added or modified in a record.

I am however wondering whether it is possible to manually trigger the same function to run "retroactively", so that it would populate the name field in records that already have an email field populated from before? 

Thank you in advance!