You can block email addresses of specific domains, or whitelist only some specifc domains via the Application Settings in the Admin area.
Note: These restrictions are only applied during sign-up. An admin is able to add add a user through the admin panel with a disallowed domain. Also note that the users can change their email addresses after signup to disallowed domains.
Whitelist email domains
[Introduced][ce-598] in GitLab 7.11.0
You can restrict users to only signup using email addresses matching the given domains list.
Blacklist email domains
Introduced in GitLab 8.10.
With this feature enabled, you can block email addresses of a specific domain from creating an account on your GitLab server. This is particularly useful to prevent spam. Disposable email addresses are usually used by malicious users to create dummy accounts and spam issues.
This feature can be activated via the Application Settings in the Admin area, and you have the option of entering the list manually, or uploading a file with the list.
Both whitelist and blacklist accept wildcards, so for example, you can use
*.company.com to accept every
company.com subdomain, or
*.io to block all
domains ending in
.io. Domains should be separated by a whitespace,
semicolon, comma, or a new line.