There exists some inconsistencies on how ECS user fields are handled across different integrations.

Specifically, when usernames are formatted as email addresses (e.g., "test.user@domain.com"), some integrations split the username and domain, while others do not. This inconsistency leads to varied results in dashboards and queries, causing confusion.

According to the ECS user fields guidelines:

Here are a few pointers to help normalize some simple cases.
- When a system provides a composite value for the user name
  (e.g. DOMAINNAME\username), capture the domain name in user.domain
  and the user name (without the domain) in user.name.
- When a system uses an email address as the main identifier, populate
  both user.id and user.email with it.

Based on the guidelines above, the criteria to apply to all the integrations would be:

• When the user name contains an email address, this field is dissected into <user.name>@<user.domain>.
• Also the user.email field is populated with the full email address.
• Append user.name and user.email to related.user.

This is how most of the integrations already proceed.