Email addresses are harvestable on API
When querying the API of gitlab.com, you can easily find email addresses (as required by GIT) of the committers.
For instance using the web site:
select id, name, description from projects where id=1815514
|1815514||www-gitlab-com||Source for https://about.gitlab.com|
And then access the API for the list of committers:
select distinct commit_author_email from branches(1815514) where commit_author_email not like '%@gitlab.com'
Result is 38 email addresses not obviously related to gitlab.com
Enable committers to indicate whether their email address may be shared through API.