diff --git a/doc/user/project/import/bitbucket_server.md b/doc/user/project/import/bitbucket_server.md
index a80ce95c163e78e8bc4ef3c78320d55be5048abf..e0dbd8422bb2df22b1682c4155b3fddfb8142b19 100644
--- a/doc/user/project/import/bitbucket_server.md
+++ b/doc/user/project/import/bitbucket_server.md
@@ -87,6 +87,9 @@ original creator.
 The importer creates any new namespaces (groups) if they don't exist. If the namespace is taken, the
 repository imports under the namespace of the user who started the import process.
 
+The importer attempts to find reviewers by their email address in the GitLab user database. If they don't exist in GitLab, they cannot be added as reviewers to a
+merge request.
+
 ### User assignment by username
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/218609) in GitLab 13.4 [with a flag](../../../administration/feature_flags.md) named `bitbucket_server_user_mapping_by_username`. Disabled by default.